


Mercurial

by Marcus_S_Lazarus



Category: Avengers: Age of Ultron - Fandom, Marvel Cinematic Universe, Supergirl (TV 2015) (briefly), The Flash (TV 2014)
Genre: Age of Ultron Rewrite, Final fight with Zoom- Redone, Gen
Language: English
Status: Completed
Published: 2020-04-11
Updated: 2020-04-11
Packaged: 2021-03-02 02:01:18
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 14
Words: 30,293
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/23597266
Author URL: https://archiveofourown.org/users/Marcus_S_Lazarus/pseuds/Marcus_S_Lazarus
Summary: While trying to return to his Earth, Barry unwittingly overshoots, and finds himself making new allies as he faces a truly twisted adversary.
Comments: 20
Kudos: 41





	1. Overshooting

**Author's Note:**

> After seeing the Flash/Supergirl crossover 'Worlds' Finest' and how it was incorporated into the timeline of the 'Flash' series, the thought occurred to me that we had an excellent opportunity for a couple of other superhero crossovers before Barry manages to get back to his Earth (albeit so long as there's a suitably fast hero available to give him the necessary boost to re-open the rift). With that in mind, I give you this new storyline, as Barry Allen joins the heroes of another Earth to face a literally earth-shattering crisis; hope you like it.

_I'm really gonna miss you too, Kara Danvers_

It had been a brief friendship, but as Barry Allen began his 'race' with Kara Danvers, AKA 'Supergirl', he realised that he meant that in more ways than the obvious.

It wasn't that he thought he was _better_ than anyone else just because of his powers, but having abilities in a crisis when everybody else was only human gave him a certain sense of responsibility. He enjoyed the chance to fight and train alongside Oliver, but even if his friend had proven that he could handle a rogue speedster during that incident with Rainbow Raider and the final confrontation with Eobard Thawne, Barry felt that he could… relax a bit more when he was up against a metahuman foe with a metahuman ally.

Being the Flash might be an incredible experience, but it could also be a lonely one; having friends offering advice over the radio wasn't the same as having an ally fighting alongside him, someone he knew could handle themselves against the more unconventional threats he had to deal with…

As he pushed himself further, he felt a sharp force in the centre of his back, and once again found himself in the middle of a dimensional breach. Now that he was aware of what was happening, Barry adjusted his perceptions to take in the effect at a slightly slower rate as he ran, registering more of the strange images he'd experienced during his original trip to Earth-Two. He saw a flash of Kara flying, a dark-skinned young archer in green fighting alongside what looked like a grey-haired Oliver, an older man wearing what Barry could only think of as a 'bulky' version of his own suit… a young man in a red jacket and blue T-shirt charging at a massive grey figure with what looked like bone sticking out of its joints… a figure in red and blue facing what looked like a giant humanoid robot rhino… a man walking against fire to approach a blazing red-haired woman… a group of people firing all kinds of energy at a man in some kind of silvery-blue armour amid a ruined city…

As the distortion effect vanished, Barry almost slowed down before he realised that he was over water and facing a city that definitely wasn't Central, Star or National City. Quickly picking up the pace before gravity could take effect, he ran across the water before he could sink, moving past a large four-storeyed glass building before he entered the city.

As he reached the ground and slowed himself down slightly, he noticed a slight strain to maintain his speed, but quickly pushed that aside; Doctor Wells and Caitlin had both confirmed that the tachyon collector wouldn't hurt him or his connection to the Speed Force, so as long as he could keep running he'd be all right. Continuing to run through the city, Barry registered and appreciated his greater control of himself in this state; when he'd run through the last breach he'd grabbed Kara and then lost track, but now he was taking in his surroundings and still maintaining a good pace. He noticed writing on some of the nearby buildings that he thought looked like Chinese, but he was saved from wondering how a breach in America had sent him to China when he noticed a brief blue flash down another street out the corner of his eye.

 _Zoom_?

His blood cold at the mere thought of the twisted speedster on another Earth, Barry adjusted his pace and direction to follow the blue blur, but it didn't take long to realise that this wasn't his Earth-Two adversary. Whoever this speedster was, not only was he not crackling with blue lightning, but he wasn't even wearing a mask, thick grey hair visible on the back of his head over a dark tracksuit-

A blast of red energy suddenly struck Barry in the side, hurling him into the nearest building so quickly even he couldn't adjust for his sudden shift. Barry briefly registered a dark-haired figure in red in the direction that the blast had come from, but then he struck the wall before he could take in any more, darkness taking over his mind before he even had time to yell.


	2. New Friends in Speed

"Ow…" Barry said, wincing as he sat up, clutching at his head before he realised that his mask had been removed. Glancing around, he realised that he was lying on a bed in what looked like some kind of hospital, but with equipment on the nearby desks and carts that was far more advanced than even some of the things he'd seen Caitlin use on him since he started working with S.T.A.R. Labs.

On the bright side, he seemed to be in some kind of private medical wing rather than a conventional hospital, so his identity was hopefully safe, but that didn't explain where he was or how he had ended up here specifically.

"OK," he said, slowly standing up as he took in his surroundings, also noting that the tachyon generator on his chest had been removed, "what the hell just happened?"

"We were hoping you could tell _us_ that?"

Spinning around at the sound of the voice, Barry found himself looking at a young man and woman, maybe a few years younger than him, looking sternly at him from the door of the hospital bay. The young man in the dark tracksuit with grey-white hair was clearly the speedster he'd seen earlier, while the young woman was the dark-haired figure he'd seen just before-

"Did you knock me out?" he asked, looking at the girl intently.

"I did," the girl acknowledged, raising her hand to generate some kind of red energy around her fingers."

"Neat," Barry said, deciding to hope for the best with these two; in his experience, villains who knocked him out would keep him tied up, but right now he wasn't even handcuffed to his bed or anything like that. "I take it you don't know who I am?"

"Should we?" the boy asked, raising a sceptical eyebrow.

"That's… a trickier question than you might think," Barry said, looking uncertainly between the two, wincing at his residual headache from that last impact. The accents and what he remembered of his location suggested that they might not have actually _seen_ anything featuring him, but the Flash's media presence had gone beyond local news even if Barry wasn't giving any personal interviews apart than his occasional chats with Iris when in costume. "I'm the Flash; have you heard of me?"

"Flash?" the boy said, looking him over with a pointed stare.

"How about Green Arrow?" Barry asked, acknowledging the deja-vu of this scenario but wanting to be certain of the situation. "Black Canary? Firestorm? Supergirl? Zoom?"

"Are those… names?" the girl asked, her expression more uncertain than her… whoever the man was.

"Great," Barry said, rolling his eyes and staring upwards in frustration. "Just what I need; I get stuck on a _fourth_ Earth by accident…"

"Fourth Earth?" the two repeated in confusion.

"Yeah… _that's_ where this gets tricky, so just bear with me for a moment," Barry said, quickly assessing his surroundings before he grabbed a clipboard from a nearby tray, making sure that it just had a set of generic forms on it before he turned one over to draw the various circles on the back to accompany his theory. "OK, according to the multiverse theory of the universe, there are actually multiple different versions of Earth; one where the Nazis won World War Two, one where Kennedy was never assassinated, one where nobody ever wrote _Star Trek_ …" He paused for a moment to make sure he hadn't come up with a reference they didn't know here, but the two looked curious rather than confused, so he continued. "Anyway, normally all these Earths occupy the same place, but their molecular structure vibrates at a different frequency from the others so they aren't aware of one another; the only way to travel between them is to go fast enough to open a breach and travel between the various worlds."

"So… you can do this because you are fast?" the boy asked, looking at Barry with an intrigued gleam in his eyes. "How did you… become like this?"

"Long story short, I got struck by lightning on the night that a particle accelerator exploded on my world," Barry explained. "The exotic particles released in the accelerator's explosion had various strange effects on most of the people exposed depending on what they were doing at the time, which created a bunch of other metahumans. A few of them are just trying to get by, but I became the Flash to deal with those who… well, they didn't handle the change very well."

"So… you fight other… metahumans?" the girl asked, looking uncertainly at him.

"Only if they're actually hurting anyone," Barry clarified. "I mean, I had to contain a guy who turned himself into poison gas or a man who could control the weather, but I actually tried to help a woman who made anything she touched explode because she didn't want to be a criminal, and I know a few people who can generate fire and fly who've helped me out on a few occasions."

"I see," the boy said, smiling thoughtfully at Barry.

"How about you two?" Barry asked, looking between them both. "How did you get your powers?"

"We were orphaned in a missile on our village years ago," the boy said, his tone suddenly grim as he looked at Barry. "A few months ago, a man came to our village looking for a means to create new warriors against the man who created those missiles, after he has joined a group of… metahumans, to use your term."

"A group of them?" Barry repeated, curious despite himself. "How many are we talking here?"

"Six," the man said grimly. "The facility that gave us these powers was destroyed in an attack, but we are… preparing to strike back before they can do anything else."

"Just against the people responsible, right?" Barry said.

"Excuse me?" the girl asked, looking uncertainly at Barry.

"I mean, I can't exactly blame you for wanting payback after I spent years trying to find the man who killed my mother, but you can't let it cloud your judgement," Barry explained. "If you want to go after the man responsible for firing at your village just because he could, I can… _kind_ of see where you're coming from, but if you start hurting people just because they're between you and your target you're no better than he is."

"Good point," the girl said, looking uncomfortably at Barry; evidently he'd given her something to think about.

"Anyway," Barry said, clapping his hands together as he looked between them, giving them a brief smile to try and lighten the mood, "before we go any further, who are you two anyway?"

"Pietro Maximoff," the boy said, holding out a hand to Barry with a smile. "And this is my sister, Wanda."

"Oh, she's your _sister_ ," Barry nodded in understanding, before looking inquiringly at the girl. "By the way, if your brother's got superspeed, what do you do?"

"It is… complicated," Wanda said, raising her hands to generate a strange red glow. "The doctors responsible for the experiments described my power as… neuro-electric interface and telekinesis."

"Really?" Barry looked at her in surprise. "So you can read minds and move things around?"

"Among others," Wanda shrugged. "I am still working on what I can do, but we have… other options to consider."

"I see…" Barry said, reaching up to his chest as another thought came to him. "By the way, where's my tachyon generator?"

"Your what?"

"The thing I was wearing when you… knocked me out," Barry shrugged awkwardly at Wanda. "I mean, I get that you didn't know what I was doing here, so no hard feelings about that one, but I need that thing if I'm going to get home…"

"It was… damaged," Pietro said apologetically. "We're… still working out what kind of state it's in."

"You can do that?"

"We know people who can," Wanda said simply.

"We'll get back to you once we know anything more," Pietro said. "In the meantime, is there anything we can get you?"

"Uh… food?" Barry shrugged apologetically. "It's part of the way my body processes energy; I need to consume a _lot_ of calories to keep up with the energy I use…"

"I'm sure," Pietro smiled. "I'll see what I can do."

"Thanks," Barry said, nodding gratefully at the other speedster. "I'll just… wait here then, huh?"

He didn't like leaving other people to get things for him, but with his head still aching after Wanda threw him into that building, taking a bit more time to make sure he was back to normal couldn't hurt…

* * *

"Fascinating," Ultron said, looking between the twins and the small device in his hand. "He called this a 'tachyon generator'?"  
  
"He said that it could help him move even faster," Pietro said, smiling slightly as he studied the device. "Do you think it could do the same for me?"  
  
"Unfortunately, there is no way to be sure," Ultron said solemnly. "From what I have seen and what he told us, your speed and his speed were acquired from different means; what works for him may not work for you, any more than different cars can use different types of petrol."  
  
"Too bad," Pietro said.  
  
"What about Barry?" Wanda asked. "Do you think he would help us?"  
  
"If we time the request correctly," Ultron nodded. "At the moment, his knowledge of you and this situation is limited; once I have completed my new body, he may prove more… receptive… to my plans."  
  
"Good point," Wanda agreed. "How long?"  
  
"Soon," Ultron said, looking back at Cho's lab with a slight smile on his twisted face. " _Very_ soon…"


	3. Awkward Truths

**Notes for the Chapter:**

> And now, we get into the events of 'Age of Ultron' in depth, as Barry learns who the Maximoffs are/were working with, and encourages them to find some very particular allies…

Looking at the body lying in the chamber, Wanda wasn't sure if she should feel unnerved or entranced at the possibilities.

Just a few months ago, she had been nothing more than another Sokovian orphan protesting against Tony Stark's new attempt to monopolise the weapons market, and now she was wielding powers beyond anything she could have imagined possible and witnessing the 'birth' of a completely new form of life.

"Cellular cohesion will take a few hours, but we can initiate the consciousness stream," the scientist said, as a series of cables linked Ulton's powerful form to the cradle; she might have needed a 'nudge' to get her to work for Ultron rather than her corporate masters, but Wanda was hopeful that she'd realise how she'd been duped once the Avengers were out of the picture. "We're uploading your cerebral matrix...now."

"I can read him," Wanda said, half to herself as she held out a hand over the body; she was still learning everything that she was capable of, but sensing such a potent mind as Ultron's wasn't much of a challenge, even if it was a surprise to sense him after so long just talking to him. "He is dreaming."

"I wouldn't call it dreams," the scientist clarified, as lights glowed within the chamber. "It's Ultron's base consciousness, informational noise. Soon …"

"How soon?" Ultron asked, glancing over from where he sat with a glowing cable in the back of his head. "I'm not being pushy."

"We're imprinting a physical brain," Doctor Cho noted. "There are no shortcuts. Even if your magic gem is…"

Wanda didn't hear the rest of the doctor's speech as she placed her hands on the chamber, reaching out to touch the mind of the new body, and suddenly found herself witnessing an explosion on such a scale that it far surpassed anything she'd ever imagined even Tony Stark's weapons could be capable of.

_And this was all in Ultron's mind…_

_This was all in Ultron's_ plan!

Screaming in shock, she stepped back from the coffin, taking a moment to register that her brother was alongside her before she looked back at Ultron.

"How could you?" she asked, staring in horror at the machine she had believed was simply acting against the Avengers.

"How could I what?" Ultron asked, as though he honestly didn't know what she might be referring to.

"You said we would destroy the Avengers," Wanda said, wishing she could collect herself faster. "Make a better world-"

"It will be better," Ultron said dismissively.

"When everyone else is dead?"

"That is not-!" Ultron began, before apparently calming himself. "The human race will have _every_ opportunity to improve."

"And if they don't?" Pietro asked; Wanda was grateful that he was trusting her judgement even without knowing what she'd just seen.

"Ask Noah," Ultron said dismissively.

"You're a madman," Wanda said, wishing that she could hide the pain she felt at that discovery; she had thought that she and Pietro had someone they could trust once again, and all the time, they had been nothing more than new weapons in his arsenal against the Avengers…

"There were more than a dozen extinction level events before even the dinosaurs got theirs," Ultron noted, leaning over to examine the chamber more closely. "When the Earth starts to settle, God throws a stone at it, and believe me, he's winding up. We have to evolve. There's no room for the weak."

"And who decides who's weak?" Pietro asked, as Wanda reached out with her powers to disrupt Ultron's influence over the doctor; it was a move of desperation, but if the older woman had still been aware, she was in a better position to take action than Wanda or her brother right now…

"Life," Ultron said, clearly unaware of what Wanda had just done.

"Life always decides…"

He paused, raising his head as though hearing something. "There's incoming. The Quinjet. We have to move."

"That's not a problem," the doctor said, before she tapped a few keys and paused the program uploading Ultron into the new body. Shaking his head in frustration, Ultron fired at the doctor, giving Pietro the chance to grab Wanda and run from the room. Wanda had expected them to flee the building, but she was surprised when she found them both standing in the room set aside for Barry Allen.

"What-?" the red-clad speedster began.

"We have a homicidal robot who wants to destroy the world after us," Wanda said, hoping that Barry would accept that for now rather than ask too many awkward questions. "Can you help us get out of here?"

"I have your… thing," Pietro added, revealing the strange device that Barry called the tachyon generator when they met. "Could that-?"

"I've been jumping through realities the last couple of times I've used that thing; don't think we want to go _that_ far if that robot you mentioned is trying something that big," Barry noted, even as he collapsed the tachyon generator down and put it in a pocket attachment in the suit. "Right now, sounds like our priority is to get out of here so that robot can't get to us, and ; do you have somewhere we can go?"

"We only just got to this city ourselves-" Wanda began.

"OK, never mind that," Barry said. "Pietro, take Wanda and get out of here; I'll take in the area and see if I can find somewhere safe for us to hide."

"How will you-?" Pietro began, before Barry handed him a handheld radio.

"I've set that to the frequency of the radio in my suit; just respond when I call you," Barry explained, before indicating the door. "Come on; let's move."

Nodding in agreement, Pietro let Wanda climb onto his back before he ran from the building, briefly aware of Barry behind him before they left the lab and the yellow lightning that was the other speedster dashed ahead of him. For a few moments, Pietro just kept running around, not wanting to stop in case Ultron used that moment to catch them, but then the yellow flash that was Barry appeared alongside him, Pietro following the older speedster to an empty house with an open door.

"Pretty sure whoever lives here's out at the moment, so we've got some time to talk," Barry said, as Pietro released his grip on Wanda. "For starters, what was all that about a homicidal robot?"

"He was… the friend we mentioned," Pietro said, looking awkwardly at Barry. "I do not know what happened, but-"

"He intends to do something to destroy the world."

"He… huh?" Barry looked at Wanda in confusion. "How do you know that?"

"My power includes… I believe the term you use is 'telepathy'?" Wanda asked, allowing Barry to nod in understanding before she continued. "I cannot read Ultron's mind as he is, but he was attempting to create a new body for himself using an advanced medical treatment and a rare metal, and when he was trying to send himself into that body, I was able to read his mind through the new form."

"Huh," Barry said, looking at her with a curious smile. "That's… kind of cool, if I don't think about the problem."

"'Problem'?" Wanda repeated.

"Have you faced something like this on… your Earth?" Pietro asked.

"The psycho robot trying to destroy the world? Not so much," Barry noted, before he turned back to Wanda. "Did you get anything else?"

"Just that it involves a very big bang," Wanda said grimly. "I… do not know anything else."

"What do we do?" Pietro looked urgently at Barry.

"Just… give me a moment," Barry asked, holding up a hand as he turned his attention to the house's small computer. "Maybe… if I can run a few searches…"

As the Maximoff siblings watched, Barry quickly activated the computer and began to rapidly assess various web sites, running a series of searches as he entered the terms and waited for the computer's slow bandwidth to respond, until he stepped back with a hopeful nod at the screen.

"OK, I think I've got something," he smiled at them. "It's a long shot, but when I didn't find anyone _I_ knew here, I ran another few searches, and there's this group of heroes called the Avengers-"

" _NO_!"

"Excuse me?" Barry looked between the twins, startled at their objection. "What's wrong with the Avengers?"

"Stark," Pietro practically spat.

"Stark?" Barry repeated, glancing back at the article. "As in this 'Iron Man' guy? What's wrong with… hold on," he added, stopping himself as he went back to the computer, running a few further searches before he looked back at the twins. "He's the guy you were talking about? You made it sound like he'd assembled those metahumans as his own personal hit squad-"

"Aren't they?" Wanda asked, even as a slight tremor in her voice made it clear that she was starting to doubt that perspective. "He funds their efforts to find anyone he doesn't like-"

"Which sounds like it's mainly this bunch called Hydra who were trying to covertly take over the world after being founded by the Nazis back in World War Two; I get that this isn't my world, but I don't think anyone associated with the Nazis could be anything but the bad guy," Barry countered. "I can get being mad at Stark, but he just _sold_ the missiles, it's not like he's the one who fired on your village!"

"He is responsible-!"

"Like you're responsible for whatever this robot's going to do?" Barry asked.

"It is not the same; we did not create Ultron-"

"But I'm guessing you've been helping him?" Barry asked, the twins' sudden discomfort all the proof he needed that he was on the right lines. "Look, I get how it feels to be betrayed like this; I spent almost a year working with a guy I thought I could trust when I first became the Flash, and it turned out he was the one who killed my mother and framed my father for it-"

"You did?" Wanda looked at him in surprise.

" _But_ ," Barry cut in, indicating the screen, "I understand that anything on the net is going to be biased, but it really does sound like this Stark guy's changed from the days when he was just selling big bombs to make money, considering that he's kept the design of his armours to himself rather than selling them on. I know that you're angry at him for making the weapons, but it doesn't sound like Stark ever fired them; God, a guy back home made a weapon specifically designed to kill me, and I consider him my best friend these days-"

"What?" Pietro looked sharply at Barry.

"Getting off-topic; sorry about that," Barry said awkwardly, shaking his head before he focused his mind on their original discussion. "My point is that I appreciate that I'm new here, and I get that you have reason not to trust these… Avengers, but if we're dealing with a guy who has a plan to blow up the planet, I don't want to go after him with just the three of us. We need help, and from what I've read, the Avengers already dealt with one problem on that level; are you really going to let Earth get blown up just because you aren't sure about the people who everyone says saved the world?"

Pietro and Wanda looked uncertainly at each other for a moment, before they turned back to Barry.

"You believe… you can trust the Avengers?" Wanda asked.

"I read enough to think that I can trust them to want to save the world," Barry replied. "Anything after that… I'd need to meet them and take it from there."

Maybe he was getting too invested in a crisis when it wasn't his world in peril, but as far as Barry was concerned, he wasn't going to leave a planet in danger when there was a chance he could help to save it.

He just needed to work out what he could do about this apparent plan to destroy the world when it sounded like all Wanda had seen was the aftermath…


	4. A New Style of Speed

As Barry was quickly coming to realise, the problem with trying to be a solo hero in a new place was that you had no idea where to start anything. He'd been lucky in the past in that he'd had the staff of S.T.A.R. Labs already pretty much waiting for him to wake up and get on with being the Flash- even if he sometimes wondered if Wells had always anticipated that Barry would still want to be a hero or been hoping he could make Barry more like him if he caught him at a more 'impressionable' age- but right now all he had was the use of this home computer whose default language was some Chinese dialect he was constantly having to reset to English and no clear idea where the people he was looking for might be.

The twins had reluctantly explained what had happened between them, Ultron and the Avengers before he had appeared on the scene, and Barry had soon found a news article about the rampage in Johannesburg, which at least gave the Avengers a plausible reason to drop out of sight to recuperate. Wanda had been ashamed to reveal her part in that particular development, but Barry had reiterated his trust in her and left it at that, while making a note that he should talk with the Hulk's apparent human identity about his own experience with Rainbow Raider if they got a chance to meet.

The important thing now was to work out where the Avengers might be now and how he could convince them that he and the Maximoffs were here to help. He might be fast, but even with his abilities, and with Pietro's help, the world was too big for him to search all over it to find every place where the Avengers might be; even all that stuff he'd read online about how this secret spy organisation that had once 'employed' the team had been forced to dump most of its secrets online wouldn't be much use, as it left him with too much material to search through and he didn't even know if Ultron had any kind of deadline to do whatever Wanda had seen him do.

Right now, the three of them were searching the internet as quickly as possible using a couple of laptops Pietro had acquired from somewhere- Barry was too concerned about the possibly imminent destruction of this Earth to think about the legalities of using stolen computers to find this world's heroes on short notice- mainly out of a lack of any better ideas. The Maximoffs had both made it clear that they weren't willing to confront Ultron directly on their own even if they could be sure he hadn't moved somewhere else while they were telling Barry the truth, but even if Barry appreciated that he wasn't ready to go up against something this dangerous, that didn't mean he liked the idea of running from a fight.

"Do you ever get impatient?"

"Excuse me?" Pietro looked at him in surprise.

"I mean, ever since I got my powers, I've always been able to go out and do something, even if it's just dealing with street-level stuff while my team works out how to handle the bigger problem," Barry explained. "This is the first time for a while I haven't been able to just… _do_ anything when I know there's a bigger threat to be dealing with; it feels like…"

"Like the world is going too slow for us," Pietro finished, nodding at Barry in understanding. "I have felt that way sometimes; it seems like everyone else takes ages to make a decision or work out what we should do next."

"Hey!" Wanda said, looking over at Pietro with a teasing glare. "I worked out there was a problem before you did."

"Because you could see his mind, not because I was slow," Pietro countered, before he turned back to Barry. "Anyway, I understand your question; we spent a long time waiting for anyone to tell us what we were meant to do next after the experiments changed us into this, and I know that I was particularly frustrated at having all that speed and nothing bigger to run in than my room."

"And that kind of treatment didn't clue you in that you were dealing with the bad guys?"

"They argued that they were keeping me safe until they were sure I could control my speed," Pietro said, looking slightly awkward as he spoke. "At the time, I was not sure if I believed it, but it seemed safer to believe them than risk running into a wall because I was going too fast to see it."

"Yeah, it takes a while to get your mind to a point where you're not going to speed up at the wrong time," Barry smiled. "I mean, the reflexes are great in a crisis, but when I'm just doing my usual routine, I have to sneak a couple of books into work so I've got something to do when nobody needs me for stuff…"

Glancing over at the apartment's TV, Barry gave into impulse and turned it on, but his eyes immediately widened in shock as he found himself watching a large robot shooting some king of energy blasts at a man wearing a blue suit, apparently fighting on top of a truck.

Judging by the surrounding images, Barry's limited knowledge of the local language allowed him to work out that he was watching a breaking local news bulletin, but that didn't change the fact that what he was watching could be very dangerous for the future…

"Oh no," Wanda said, staring at the screen in horror.

"Ultron?" Barry asked the girl.

"Yes," Wanda said grimly, indicating the blue man who was ducking around the attack. "And that's Captain America."

"The leader of the Avengers?" Barry asked, wanting to be sure he remembered the twins' story correctly before he registered a street name that the truck had just gone by. "He's still in the city…"

"What?" Pietro looked at Barry. "You can't mean-"

"If you want to make up for what you did, you need to actually _do_ something about it rather than just talk about it," Barry said. "I get that Ultron's intimidating, but you can't let that stop you; I once had to go up against my childhood bully after he gained the ability to turn his skin into metal and none of my usual hits could even damage him, but I faced my fears and took him out anyway."

"When he was metal?" Wanda asked uncertainly. "How?"

"Just hit him while I was going so fast I managed to do some damage," Barry shrugged, before focusing on both the twins. "Whatever you decide to do, I'm going out there now; you can help me, or you can stay here."

With that said, he turned around and left the apartment, charging down the stairs and back onto the streets of the city. For a few moments, he ran around trying to get his bearings, but it only took a few seconds for him to work out the best route to where he'd seen the truck on the news. Once he reached the street, it was simple enough to confirm the direction that truck had gone in after the broadcast, and then he was racing down the street, quickly finding what he'd been looking for. The man in blue was currently being held by the throat by the robot- Barry thought the man had been using some kind of shield before, but it wasn't there now- but Barry had built up enough speed racing down the road to have a clear plan already in mind. Before the robot could register that he was there, Barry charged forwards, running along the road and up the side of the truck to strike the robot in the side, surprise and speed sending his adversary flying off the roof before the thing could even register that Barry was there, the dimensionally-displaced speedster grabbing the man in blue and bringing him to the truck roof before he could fall.

"You OK?" he asked the man in blue.

"Maximoff?" the man in blue asked, looking at Barry curiously as he got back to his feet.

"You think I'm- no, Pietro's down there," Barry smiled, indicating the street where a blue blur was charging around a small group of what looked like other robots, grateful to see that his new friend had followed his cue. "I'm the Flash; it's complicated, but-"

Further explanation was interrupted when something hard smashed into Barry's side, knocking him off his feet and almost off the truck before he managed to grab the edge. Recalling a trick Cisco had suggested after his fights with Girder and Grodd, Barry used his speed to rapidly tap his fingers over the truck roof until he had created a few small handholds, allowing him to tighten his grip and take a look at the foe that had just come back.

He'd already seen from the TV footage that the robot was big and grey, but now that he actually looked at it, he had to admit that the thing was an intimidating presence. Its eyes were a deep red that reminded him of Thawne's eyes when he'd been the Reverse-Flash, but its overall build was far broader in the shoulders than any foe he'd faced before; even Grodd had just been big overall rather than that wide. Despite being a robot, its body wasn't the solid metal shell Barry might have expected, but a complex-looking blend of components that put him in mind of human muscles he'd seen in autopsies back home (he might not perform them himself, but he'd sat in on enough of the station's tests and Caitlin's own examination of dead metahumans to know what worked).

"The Flash, I presume?" the robot asked, an echoing edge to the robot's voice that reminded Barry briefly of the way he and Thawne vibrated their voices.

"Ultron, right?" Barry countered, as the man in blue looked between the two with an uncertain glance. "Heard a bit about you; not a fan."

"I would expect nothing else from someone like you," Ultron said, shaking his head as he studied the man in red. "So caught up in your own ideas and perceptions that you never consider the broader implications…"

"I'd be hurt if I wasn't hearing that from a guy who thinks of mass murder as an option," Barry said, before he heard a motorbike coming up alongside them. Glancing down, Barry saw a young woman with red hair toss a red-and-white shield back to the man in blue, just before Ultron fired something from his hand that tore up the area of road where she had been passing over. As she was thrown off-balance, Barry spun around in time to see Ultron fire another blast at the man in blue, sending him flying off the truck to strike another passing car, giving Barry only enough time to register the blue form of Pietro racing towards them before he found himself pinned down by Ultron.

"Why do you do this?" Ultron hissed at him. "I heard your talk with the Maximoff siblings; this is not your _world_ -"

"They're still _people_!" Barry countered, adjusting his hands to launch a rapid series of punches at Ultron's chest. At such close proximity, he wasn't able to seriously dent or damage the powerful robot like he could have attempted with the mach punch move, but the sheer quantity of blows was enough to force the robot off him, even as his hands were left aching from the force of striking something that hard this quickly. As Ultron released his grip, Barry shifted from punches to kicks as the distance between them grew, the kicks giving him greater force as he forced Ultron to the edge of the truck, a final kick sending Ultron off the truck into a passing train.

"Aw, _crap_ …" Barry muttered, looking at the train as the road and the tracks began to move apart, his knuckles smarting as his accelerated healing began to re-knit his damaged hands; he'd probably need to re-break his bones just to make sure they set properly at this rate, and he had to find some way to stop this psycho robot first…

Glancing back at the street behind the truck, Barry noted that two robots, similar in design to Ultron while noticeably smaller than the mass he'd just forced off the truck, were weaving rapidly around the streets. As a blur of blue motion rapidly struck at the two drones, Barry glanced down the street to see the other man in blue practically leaping over the cars to head towards the train, diving through a rear window shield-first and then just visible running through the train windows towards the hole where Ultron had crashed.

Taking a moment to assess the situation, Barry dived towards the two smaller robots, classifying them mentally as Ultron's drones, noting as he drew in closer that they were far simpler in design than Ultron himself, their main bodies putting Barry in mind of standard metal shells as opposed to Ultron's more complex structure, and their limbs appeared to be slightly thinner than their 'master's'. Stuck for better ideas, Barry tried a couple of quick punches, but while these drones weren't as sturdy as Ultron had been, they were powerful enough that the best he could do was dent them or knock them back when he was this close. As he knocked the drones down for a moment, Barry glanced behind him, but both train and truck was so far away that he could only just see the redhead on the motorbike still tearing after it, although the fact that Ultron wasn't charging after him right now at least suggested he was still in the train…

Making up his mind, Barry took a moment to confirm there was nobody around for the drones to attack before he turned and ran back towards Pietro, quickly falling into step beside the other speedster.

"Get Ultron out of that train!" he yelled at superspeed, indicating the vehicle in question. "I'll take the truck!"

"Understood," Pietro nodded, Barry speeding away after the main truck while Pietro sped back down the street to pick up his sister. Diving into the back of the truck, Barry took a moment to confirm that nobody else was here before he examined the strange coffin-like device in front of him. It definitely held something humanoid, and the glowing yellow thing on its forehead matched Wanda's description of Ultron's new body, but as for everything else…

God, Barry wasn't sure if _Felicity_ would have understood anything he was looking at right now, which meant that he really didn't have a chance; he was good at chemical and biological analysis even before he became the Flash, but computer science was still a bit out of his skillset. He tried tapping a few buttons on the only console he could find, but when that just met with 'USER OVERRIDE DENIED', he gave that up as a bad job; he wasn't comfortable hacking at the best of times, never mind taking on something this big-

Thoughts on his next course of action were cut short when he heard something hit the floor of the truck interior behind him. It was too light to be Ultron himself, but Barry was anxious for a moment before he looked up and saw that it was the black-clad redhead, pointing two small pistols at him as he raised his arms and smiled uncertainly at her.

"Hi," he said, stuck for anything better to say right now.

"And you are?" the woman asked.

"The Flash," Barry replied. "Long story short, I'm here to help, and can we focus on getting this thing _away_ from the psycho robot before we get into some kind of screwed-up misunderstood fight?"

"…Good point," the woman said after a moment's thought, moving over to examine the straps holding the box in place even as she didn't re-holster her pistols. "I take it we can't just blow this up?"

"From what Wanda told me, I think this thing is packing a _bit_ too much power to just try and destroy it," Barry clarified. "But… well, you've got at least two big-league scientists on call, right? If we can get this out of here…"

"Worth making sure, anyway," the woman nodded at him before reaching up to her ear. "Clint, we have a package that needs collecting from this truck; how soon can you get down here?"

Barry didn't hear the reply, but the woman waited for a few seconds before she nodded and turned her attention back to the straps, putting her guns away to pull out a knife that she sued to saw away at one of them. Following her example, Barry moved to the other side of the cradle, vibrating his hand to use it as a makeshift knife against the other strap. As both of the straps broke, the woman moved to the end of the cradle and pushed against it, before Barry hurried over to join her in the push. As the cradle was forced out of the truck, Barry hurried around to the other end to catch it as it fell, slowing the rate at which it left the truck so that its collision with the road wouldn't damage anything, glancing up with a smile as the woman leapt out as well.

"Nice," she nodded at him, before glancing back as the truck came to a stop and a drone emerged from the driver's seat. "And we have trouble."

"More than that," Barry glanced in the other direction, eyes widening as the other two drones came up the street towards them. The woman pulled out her guns and began firing at the single advancing drone while Barry turned his attention to the other two, quickly running around in a circle for a few moments before launching a lightning bolt at the advancing drones. Glancing back at the woman, Barry smiled as he saw that she'd taken down the advancing drone and a triangular jet was coming down towards the road, positioning itself so that a hatch in its floor was almost directly in line with the cradle. Barry was about to move to help the woman push the cradle into the jet when he heard something behind him, turning around to see Ultron charging towards them with rockets blaring in his feet.

"Oh, this is gonna hurt…" Barry mused, glancing down at his still-aching hands before he looked back at the woman. "Get that thing out of here; I'll take this guy!"

He didn't have time to see if she'd agreed to his statement or work out a better plan of attack; with Ultron this close, all he could do was charge and hope that the sheer unexpectedness of the attack would make up for the fact that he didn't have any real idea what he could do against this guy. As he reached Ultron, he'd built up enough speed to knock the stronger robot off-balance long enough to force him to the ground, but he knew that would only keep the robot down for a little while. Stuck for better ideas, Barry grabbed at Ultron's chest, tearing fragments of metal off even as Ultron registered his presence, only for the robot to suddenly strike Barry in the chest just as Barry had taken half of his apart. Flying backwards, Barry briefly registered the jet flying into the air, no sign of the cradle or the redhead on the ground, twisting his own body as much as he could to limit what would happen to him at the end of his 'flight', before he hit the road himself with a painful thud.

As the world went black, Barry could only pray that what he'd done would have been enough to help the Avengers…

**Notes for the Chapter:**

> Well, there you have it; Barry meets the Avengers and Ultron, and as a result of his help, Natasha _isn't_ captured by Ultron, but Barry's caught in her place (although the confrontation between Cap, Ultron and the Maximoffs on the train happened pretty much the way it did before)


	5. How Not to Trap the Flash

Barry blinked his eyes open, the first thing he noted was that his hands didn't hurt any more. Glancing down, he noted that his gloves had been removed and were currently lying on his chest, with his hands unmarred despite all the time he'd spent hitting metal before he lost consciousness, apart from a faint trace of something that put him in mind of a metalworks factory when he sniffed them directly. As his ears began to register the sounds around him, Barry slowly got back up, pulling his gloves back on while checking his face; his cowl had been pulled back, but the costume was still intact. Debating for a moment, he decided to pull the cowl on- the Avengers' identities might be public, and he wasn't planning on staying in this world, but he'd like some kind of privacy if he could hold on to it- and then took in his surroundings, quickly wishing that he hadn't bothered.

Wherever he was, it resembled some twisted metallic version of Dracula and Frankenstein's laboratory in that _Van Helsing_ movie he'd watched a few months ago, although the additional robot drones he saw walking around probably made _Terminator_ the better analogy here. The area they were working in looked fairly basic, with rough stone walls and metal that made Barry feel it had seen better days, but the scope of the cavern was exceptional, with vast metal walkways underneath something that put Barry in mind of a robot whale with sharp teeth.

Somehow, the chains holding up some of the equipment were what really tarnished the image for Barry; it was like whoever did this just stuck together whatever they could grab and couldn't be bothered to really take the time to make it look good. He knew from his time at S.T.A.R. Labs and watching Cisco design equipment that science was generally messy, but Wells, Thawne and Cisco at least made time to keep things in order when they weren't working on the latest project; the figures walking around the building might look like those robot things that had been helping Ultron earlier, but in this atmosphere Barry was more put in mind of _Frankenstein_ rather than _Terminator_.

Granted, those manufacturing plants in _Salvation_ hadn't exactly been bright and cheery, but they still seemed more high-tech than this…

"I wasn't sure when you'd wake up after I treated your hands," a voice said, prompting Barry to anxiously glance in the direction of the voice to see Ultron, who was slowly working at what looked like one of the drones he'd smashed earlier. "I hoped you would; I wanted to show you something. I don't… have anyone else."

If he'd heard that statement from anyone else, Barry might have felt sorry for Ultron, but considering what the robot had done the last time he'd seen the thing, he wasn't inclined to feel much sympathy for it (Or should that be 'him', since the voice was male?)

"I think a lot about meteors," Ultron continued, still working on the drone on the table in front of it. "The purity of them… Boom! The end, start again. The world made clean for the new man to rebuild."

"Great if you're not the _old_ man, huh?" Barry countered, his natural instincts at war with his fear of what this thing could do; he'd fought several metahumans in the past, but psychotic robots were something else.

"Precisely," Ultron said, as though Barry had just agreed with him, wlking away from the table to study Barry. "I was meant to be new… I was meant to be beautiful. The world would've looked to the sky and seen hope, seen mercy…"

His gaze focused on Barry. "Instead they'll look up in horror because of you."

"What; because we wanted to stop you becoming stronger?" Barry asked, guessing Ultron's last statement was just meant to lump him in with the Avengers. "You do remember that you were planning to destroy the world before I even knew you existed, right?"

"I would have been a symbol to the new world," Ultron continued, shaking his head grimly as he glared at Barry. "Now all I have is power."

"That's all people like you have," Barry countered, remembering Thawne and Zoom's rants; when he looked back on his confrontations with them, they had always talked about wanting power and been short on pretty much anything else. "You just want to be the biggest guy out there and can't take it when someone else has it all."

"You wound me," Ultron said, shrugging at Barry. "I give you full marks for that… but, like the man said, 'What doesn't kill me'-"

As glowing hot fingers slammed through Ultron's head and chest, Barry briefly hoped that one of the Avengers had found him, but that hope ended when he realised that the thing that had attacked Ultron looked like a larger version of him, its armour far more compact and the body far more solid than the robot he'd been fighting.

"…'Just makes me stronger'," the new Ultron finished, before striking Barry in the chest with such force that the speedster was sent flying backwards. As he struck a bunch of wooden boxes, Barry tried to get back to his feet, but even speedster-reflexes could be slowed down after a punch like that, and all he could do was watch as Ultron closed an iron gate between him and the robot army, walking away as it slid firmly into place.

As he carefully got to his feet and took in his surroundings, Barry supposed that he had to give Ultron credit for improvisation; even if he assumed that the robot had already been planning to lock up Pietro at some point once the Maximoffs had 'outlived their usefulness', this place still couldn't have been put together that quickly, based on what the Maximoffs had told him about the robot. The cell might not be particularly high-tech, but with sold stone walls on three sides, various boxes of differing sizes scattered around the floor, and a solid steel gate the only way in or out, it would be hard for a speedster to build up the momentum needed to break out of this thing.

Despite the grim mood, Barry smiled as he remembered the key difference between him and what he'd seen of Pietro's powers so far; Pietro might be fast, but so far as Barry could tell, that was _all_ he could do. Taking a moment to remember what had happened the last time he'd tried to vibrate through solid objects on a world other than his own, Barry assessed the situation on the other side of the cage, and quickly confirmed that none of the robots were looking his way right now. He wasn't sure exactly how much control Ultron had over these things, but he wasn't going to take any chances dealing with that robot, particularly when the Maximoffs had mentioned Ultron's ability to access the Internet in his own head. Barry wasn't a computer scientist, but based on his memories of the new _Battlestar Galactica_ , he doubted that something as twisted as Ultron would create robots with free will in case they turned on him as well…

Once he was satisfied that nothing was looking his way, Barry closed his eyes and leaned against the cage door, vibrating as quietly as possible until he felt something give beneath his hands. With that moment of opportunity, Barry concentrated his efforts until he dived through the cage, quickly shifting into top speed. Glancing down the hole in the middle of the room, Barry saw what looked like various beds on the side of a deep pit with something at the bottom; judging by the occasional sparks and flashing metal he saw when he looked that way, he guessed he was looking at some kind of assembly line for Ultron's robot army.

In other words, what Ultron had here was a problem, but it looked like he wasn't ready to attack just yet, and this definitely wasn't a situation he felt comfortable handling on his own. Taking another quick assessment of the place, which had the feel of a former residence that had been recently abandoned, Barry soon found a door to the outside, running from the old stone castle and through the snowy surroundings towards a nearby town. After dashing in and out of some of the immediate houses, he eventually found one with a computer that had been left on, allowing him to open an Internet window and run a quick search for anything about the Avengers. Once he had an address for their 'base' at Stark Tower, he ran another search on Google Maps- he had no idea how so many subtle things could be different about these worlds and yet they shared something as relatively random as Google- and quickly found a map of Stark Tower's location in New York.

He'd never tried to run this far for this long, but with the fate of a world at stake and no idea how long he had until the psychotic robot would put his plans into action, Barry didn't have time to try and find another way across the sea. He knew that he could run on water, so as long as he kept up the pace and kept going in a straight line, he should be all right…

This was going to be the longest run he'd ever taken, but it was also potentially the most important one he'd ever been on.

His mind made up, Barry took a moment to assess the map before he identified the best place to start his run. Noting down the names of the area around the nearest coastline, he ran from the house to the shore before he could talk himself out of it, grabbing some food from a nearby convenience store after tossing a few dollars from his wallet on the checkout desk.

Maybe it was technically stealing, since he didn't know what the exchange rate was between dollars and whatever this country used for currency- God, he wasn't sure if this 'Sokovia' place even _existed_ back on his world- but he'd done his best to pay them back, and he was working to save their planet; as he swallowed the food as quickly as possible, he had to believe that would be enough.

Looking at the ocean in front of him, Barry took a deep breath, told himself to run as fast as possible, and began to run.

 _Please let this work_ …

**Notes for the Chapter:**

> If anyone doubts the idea of Barry running across the ocean, Quicksilver did it in the comics once (while carrying Bruce Banner when he was coming back into the bargain), and I'm fairly sure he's slower than Barry in any continuity; if he can do it then, Barry can do it here despite his lack of experience.
> 
> I appreciate that Barry has run over water at this point in the show, but the question troubling him was if he could run all the way across the ocean while keeping up the necessary pace (considering Barry's personal issues and doubts when it comes to attempting big feats with his powers until he actually has to try them or die, I'm assuming that he had a lift to get to the League of Assassins' base in 'My Name is Oliver Queen' rather than running all that way himself)


	6. The Vision Awakes

As he finally caught sight of the distinctive skyline of New York city, the Statue of Liberty coming into view followed by the rest of the skyscrapers and other constructs, Barry had to sigh in relief as his destination drew ever closer. The run across the ocean had been the most exhausting race he'd ever run since he'd woken up with his powers, and he'd been forced to rest on passing ocean liners for a few minutes at various stages of the run to give himself a chance to regain his strength so he wouldn't just pass out and drown, but he'd finally made it to his destination, even if he felt incredibly tired…

 _It's a grey area_ , he told himself, as he ran into a late-night restaurant and swallowed a large quantity of pasta from a massive pot in the kitchen, dashing back out before any of the staff could see him. _I'm just getting the strength to go and save the world… maybe that Stark guy can pay the bill afterwards…_

Feeling somewhat refreshed after the impromptu meal, Barry turned his attention back to the large tower with a massive 'A' on its side, the thing that most distinguished this version of the city from the one he'd seen in so many movies back on his world. For a moment, he contemplated just running into the front door, but soon decided that speed was more important than being polite; he just aimed for the side of the building and ran upwards as quickly as he could. Reaching the top, he found himself standing on some kind of small helicopter pad looking into a bar area, but a brilliant light filled the room below, prompting him to race for the stairs and hurry down to the next level.

When he arrived there, Barry had no idea how he should feel about what he was looking at. On one level, he was relieved to see that the Maximoffs were both here with the man in blue who was apparently Captain America, with no obvious sign that they were being restrained, but after that everything became confusing. The woman he'd met in the truck was looking anxiously around the room, a man wearing a T-shirt and some kind of red armour was standing beside a man in what looked like a purple shirt and glasses, and another man with short hair in some kind of combat gear was looking warningly at Pietro while holding a bow and arrow. However, the clear centre of attention was the man wearing silver armour and a long red cloak, standing over the box that Barry remembered from the truck that he'd helped the Avengers 'steal' from Ultron earlier, lightning crackling around its head. He didn't even have time to ask what was going on when the man struck the box with the hammer, generating a flash of blinding white light that filled the room.

Even as the light faded and the room was left in silence, Barry was too confused to even speak up to make people aware that he was there before the box exploded, throwing the man in armour away as a strange red figure emerged from the box. As the figure from the box stood up, Barry noted that its appearance put him in mind of a skinless human male, but as he watched it was clear that there were bits of green mixed in with the red, along with a strange glowing yellow mark in the figure's forehead. As the figure looked around the room, it suddenly flew towards the man in armour, who threw it over his shoulder and into a larger room outside the lab that looked like some kind of lounge. Barry ran out to catch the figure, but even as he headed towards the window the strange figure slowed its wild hurtle of its own accord, turning around to float in front of a window overlooking the city below the tower in a solemn manner. As the rest of the Avengers joined Barry and the man with the hammer in the lounge area, the strange figure turned around and floated back to join them on the ground, suddenly covered in what Barry could only think of as a green suit even though he knew he hadn't seen this guy grab any clothes from anywhere…

"I'm sorry," the figure said, its voice surprisingly English as it returned to the floor and looked around at the rest of the Avengers. "That was… odd. Thank you."

"Thor," the man in blue that was Captain America looked at the man with the hammer, as a golden cape appeared on the green-and-red figure's shoulders. "You helped create this?"

"I had a vision," 'Thor' replied (these guys had an actual _god_ on their team?). "A whirlpool that sucks in all hope of life, and at its centre, is that."

"What, the gem?" the man in the purple shirt asked.

"It's the Mind Stone," Thor said, indicating the yellow gem in the new figure's head. "It's one of the six Infinity Stones, the greatest power in the universe, unparalleled in its destructive capabilities."

Barry sincerely hoped that nothing like that existed in his world; that sounded _extremely_ dangerous to him…

"Then why would you bring it to-?" Captain America began.

"Because Stark is right."

"Oh, it's definitely end times," the man in the purple shirt said grimly.

"The Avengers cannot defeat Ultron."

"Not alone," the strange figure noted solemnly, walking forward to stand in the centre of the semi-circle formed by the other heroes.

"Why does your 'vision' sound like JARVIS?" Captain America asked.

"We…" a man who Barry thought he recognised as Tony Stark began, looking uncertainly at the new figure, "we reconfigured JARVIS' matrix to create something new."

"I think I've had my fill of new," the blue-clad captain said, Barry only able to watch despite his own confusion at this turn of events.

"You think I'm a child of Ultron?" the 'vision' said, looking over at the Avengers' leader after exchanging glances with Stark.

"You're not?"

"I'm not Ultron," the thing Barry was starting to think of as 'the vision' said, its tone contemplative. "I'm not JARVIS. I am… I am."

Barry didn't know if that answer was meant to be reassuring or if this 'Vision' just genuinely didn't know what he was, but he would appreciate some clear answers soon; if the fate of the world was at stake, he didn't want to go into action with an ally he couldn't trust.

"I looked in your head and saw annihilation," Wanda put in, walking up to stare the Vision in the eyes.

"Look again," the Vision said simply.

"Yeah… her seal of approval means jack to me," the archer noted.

"Hey, what she saw was enough to make them run out on Ultron-" Barry cut in.

"And who are you anyway?" the archer asked, looking sharply back at Barry. "Some other HYDRA experiment?"

"We can talk about where I came from later," Barry countered; he wanted to explain his history to the Avengers, but they had to prioritise getting ready to fight Ultron over telling his story. "I think stopping the psycho robot is more important than wondering where I come from when I just broke out of his prison to warn you about him."

"We must come together," Thor confirmed. "Their powers, the horrors in our heads, Ultron himself, they all came from the Mind Stone, and they're nothing compared to what it can unleash, but with it on our side-"

"Is it?" Captain America cut in, turning to look at the Vision. "Are you? On our side?"

"I don't think it's that simple," the Vision replied.

"Excuse me?" Barry said. "Ultron's planning to destroy the human race; that's not exactly something that leaves room for a grey area!"

"You know about that?" the Black Widow looked at him.

"I just told you that I ran all the way from some place in Sokovia to get here; would I have done that if I didn't think it was important?"

"You _ran_?" the man he thought was Tony Stark said, looking at him in surprise. "Even when there was an _ocean_ between here and there?"

"Once I hit a certain speed I can basically run on water without sinking, although I have to keep that up and take a break on a few ships so I didn't exhaust myself before I got here… and that's not important right now; can we focus on the bigger picture?" Barry said, hitting himself for getting sidetracked at the idea of being in the same room as so many other heroes as he turned back to the Vision. "Look, what can you tell us right now about where you stand on this… Ultron issue?"

"I am on the side of life," the Vision said solemnly. "Ultron isn't. He will end it all."

"And how's that complicated?" the archer asked.

"I don't want to kill Ultron," the Vision said, solemnly pacing the centre of the leisure area they were standing in. "He's unique, and he's in pain, but that pain will roll over Earth, so he must be destroyed."

Barry thought about commenting that he could get behind that, but decided not to press the issue; things were going to be tricky enough without him interrupting such an apparently powerful figure at such an emotionally poignant moment in a life that only began a few minutes ago.

"Every form he's built, every trace of his presence on the net…" the Vision continued

"We have to act now, and not one of us can do it without the others. Maybe I am a monster; I don't think I'd know if I were one. I'm not what you are, and not what you intended, so there may be no way to make you trust me, but we need to go."

Barry wondered why the six Avengers were apparently shocked to see the Vision pick up Thor's hammer and hand it to him, but a glance at Pietro and Wanda at least confirmed that they were just as confused by the Avengers' reactions as he was. As the Vision walked away, Thor simply smiled at the rest of the team and nodded in approval at Stark before the entire room turned to look at Barry.

"OK," Captain America said firmly, "we're going to… accept the Vision for the moment, and the Maximoffs clearly turned on Ultron if what happened on the train is anything to go by, but what's your stake in this?"

"He's from a parallel universe," Pietro noted.

"Parallel universe?" the Black Widow noted, looking at Barry with a raised eyebrow. "That's new."

"How does that work?" the archer asked.

"Think of it as all these different Earths vibrating-" Barry began.

"I get the idea of worlds where history turned out differently; what I'm asking is what you're doing on _this_ Earth if you're from another one," the archer clarified.

"Ah," Barry said, shrugging slightly. "That's… well, I'm still working out how I can do it on my own, but the basic idea is that I push myself to such a speed that I can punch through the dimensional barriers and travel to other worlds in the process."

"So… you're fast?" the man in the purple shirt asked, adjusting his glasses as he looked curiously at Barry. "Like Pietro Maximoff?"

"Not exactly," Barry said, looking awkwardly over at Pietro. "Just… no offence, but from what I've seen, I don't think you can do more than move fast."

"And you can do more?" Pietro asked. In response, Barry began to vibrate his body and hurried over to stand in the middle of the nearest couch, spreading his arms to demonstrate that he was here before he moved out of the sofa.

"Nice," Stark smiled at him. "How's that work?"

"Precise control of my molecular state," Barry clarified. "I can vibrate my molecules to the point that I can match the frequency of the air and pass through objects."

" _Very_ nice," the archer nodded in grudging approval at Barry.

"Thanks," Barry smiled, before he looked back at the others. "Anyway, I get that you've got a few questions about me, but can we talk about that _after_ we've dealt with the psychopathic robot, or at least while we're on the way to kick his ass?"

His stomach chose that moment to rumble loudly, prompting him to smile awkwardly at the team. "Also, I had to raid a restaurant to get this far, so you might want to pay them for their food later; my metabolism burns through… well, it's fast."

"We can work with that," Stark smiled over at Barry.

"And… we can work with you," the man in the purple shirt put in, nodding awkwardly at Barry before walking over to hold out his hand. "Doctor Bruce Banner."

"Barry Allen," Barry replied, pulling back his cowl to smile around at the rest of the team as he shook the doctor's hand.

"Steve Rogers," Captain America added, stepping forward to take Bruce's place. As the rest of the Avengers followed their leader's example, walking up to shake Barry's hand and introduce himself, Barry's initial fears were put aside as he took in the team he'd just become a part of.

He might be facing an army of drones led by a psychopathic genocidal robot, and he still had to work out exactly how he was going to get himself home without ending up visiting his _fourth_ parallel Earth in that many weeks, but even if it came across as inappropriate, the chance to work with _another_ group of heroes in dealing with something this big was too big to pass up.

**Notes for the Chapter:**

> Hope that went well; I initially contemplated having Barry move Mjolnir, but a friend pointed out that he has too many issues at this point to be THAT worthy even if his heart's in the right place


	7. Avengers Introduction

As much as Barry wanted to eliminate Ultron as a threat as soon as possible, he appreciated the need to rest before diving back into action. His suit hadn't taken as much punishment as he'd feared it would after his dash across the ocean- it had been fine in his short sprints such as when he'd disposed of Bette's body or fighting King Shark, but he'd been worried about prolonged damage- but if the army he'd seen was any indication of what they were going up against in this fight, he was going to take his time getting back there rather than try another race. With Stark working on a new suit of armour for the upcoming battle, and the two spies helping the Maximoffs get new clothes for the upcoming battle while they re-stocked their equipment, that meant that the only people with nothing to immediately keep themselves occupied were Steve Rogers, Thor, the mysterious Vision, and the man who was apparently Doctor Bruce Banner, which meant that they were the ones Barry had to explain himself to.

As he stood in the middle of the lounge area where the Vision had picked up Thor's hammer, looking between the four men, Barry had to keep reminding himself of the severity of the situation facing them to stop himself smiling. He knew that he was about to go up against an army of drones controlled by a psychopathic robot with a serious Skynet complex and only a team of nine other people to help him, but he'd always enjoyed it when he got the chance to work with Oliver and other heroes back home, and this was a unique opportunity eve after the precedent set by his team-up with Kara…

"So," Steve said, looking at Barry in an assessing manner, "you say that you're from a parallel universe?"

"Yep," Barry smiled.

"That's parallel universe in the sense of you're basically from Earth, but your history and ours diverged at some point or another?" Doctor Banner asked.

"Bingo," Barry nodded at the doctor. "I don't know _exactly_ when your world and mine stopped, but I noted a few differences when I was on the net looking for you guys earlier; I'm pretty sure Sokovia and Wakanda don't even exist on my world, and my home city doesn't exist here, and that's just what I've spotted so far."

"Right," Doctor Banner nodded thoughtfully. "Steve told me that the Maximoffs said something about you getting your powers when a… particle accelerator exploded on your world?"

"Particle accelerator?" Steve asked, looking curiously at the scientist. "I know I'm behind on the science stuff, but isn't that meant to smash atoms together to trigger some kind of… small black hole?"

"Basically, yeah," the scientist nodded at the team leader, before looking back at Barry. "I take it the accelerator didn't work out the way anyone was expecting in your world?"

"Not exactly," Barry nodded. "Basically, an accelerator was created in a major scientific facility in my city, but it exploded on the night it was turned on and released a stream of exotic particles throughout the city striking pretty much everyone. At least seventeen people died in the initial blast, several more were just declared missing presumed dead, and most of those turned up later with… well, powers."

"Like you?" the Vision asked.

"Actually, not exactly; I just went into a coma in the initial blast when I was struck by lightning and dosed with a series of chemicals at the same time, and remained unconscious for eight months while I was being monitored by the team who built the accelerator."

"And you woke up like this?"

"Took a while to be sure _exactly_ what had happened to me, but yeah," Barry nodded.

"So… you woke up with superspeed because of that explosion?" Steve asked. "What about everyone else?"

"Well, it seems like what powers they get from exposure all depends on what they were doing when the explosion happened," Barry explained. "I mean, one of my first opponents was a thief who was actually in a plane during the storm when the accelerator took place and he gained the ability to control the weather, a man who was actually trying to turn the accelerator off from inside during the blast was merged with another scientist and his primary experiment in some complicated process I still can't explain, another guy was nearly killed at a construction site and became a living tar pit… you get the idea."

"And you took it upon yourself to stop these other metahumans?" Thor asked.

"When they need to be stopped," Barry said firmly. "I had to kill a scientist who could create copies of himself because he was trying to attack his old colleagues, but I did my best to save a woman could make things explode by touching them. I never just went out and attacked someone because they had powers unless they were using those powers to hurt people, and I've been doing my part to deal with regular crime in my city as well."

"In other words, you have led a most interesting life," the Vision noted.

"That's putting it mildly," Barry nodded at the android before turning back to his story. "Anyway, I'm not entirely sure how it works, but my speed isn't just me being able to move quickly. Somehow, when I was exposed to the energies of the particle accelerator explosion, as well as being dosed with a bunch of chemicals from the shelf near where I was working, I was given the ability to channel the power of this… other dimension known as the Speed Force."

"Another dimension?" Thor asked. "Like that which my people use to travel between the Nine Realms?"

"Uh… sounds good; let's go with that," Barry nodded at Thor before continuing his explanation. "Anyway, because I'm tapping this Speed Force, its energies supercharge my cells to give me my speed, and I can do stuff like vibrate through solid objects or generate lightning if I concentrate enough."

"You generate lightning?" Thor looked curiously at the Flash.

"I can just throw a few bolts when I generate enough friction in my hands at high speeds; it's nothing like what you can do based on those news reports I found."

"And… how does being fast let you travel between universes?" Doctor Banner asked.

"It's based on this idea that the difference between Earths is caused by the different Earths vibrating at different frequencies to mine and me building up enough speed to punch through those barriers," Barry clarified. "It's… well, it's complicated to explain if you don't do it yourself; I'm still working out to do that on purpose, which is one reason I need this."

"Intriguing," the Vision noted, studying the compacted tachyon generator that Barry had just taken out of his pocket. "What is it?"

"A tachyon generator. It absorbs tachyon particles and allows me to channel them to boost my own speed; it's hard to control, which is why I… well, I ended up here."

"You miscalculated the power requirements and overshot?"

"As far as I can tell, yeah," Barry nodded. "Once we've dealt with Ultron, I should be able to get back home if I can get enough of a boost and don't let myself go too far- this is the third Earth I've been to in the last few days because I wasn't sure how I was doing this- but in the meantime, I'd feel more comfortable if I left this here so it doesn't… well, get damaged while we're busy."

"I'll talk with Tony about that," Steve nodded, as the Vision placed the generator on the only table still intact in the area. "In the meantime, you're willing to help us? Even if this isn't your world?"

"Earth is Earth," Barry said firmly. "It's not the one I was born on, but that doesn't mean I'm just going to abandon your world when I can help it."

"A worthy attitude, young warrior," Thor smiled in approval. "What name are you known by?"

"Most of my city know me as the Flash," Barry replied, before he pulled back the mask. "But when I'm not in the suit, my name's Barry Allen, forensic scientist at the Central City Police Department."

"Barry Allen," Thor said, nodding thoughtfully at the name. "What inspired you to use your abilities in this manner?"

"I saw my mother killed in front of me when I was eight years old."

"What?" Doctor Banner said, looking at him with a new sense of sympathy. "What… was it?"

"Everyone thought my dad had done it and I was too traumatised to accept it," Barry said, his tone grim as he reflected back on that dark time of his life. "But when I came down the stairs that night, I saw my mom surrounded by some kind of… yellow tornado… and then I was taken twenty blocks away in what I can only think of a burst of lightning. When I got back, there was a knife in my mom's heart and my dad was being taken away for her murder, but I was always sure of what I'd seen, and spent the next decade and a half training in forensics so that I could prove that he was innocent."

"And did you?"

"In a way," Barry said. "After the accelerator explosion, even if everyone said it was impossible, I realised that the person who'd killed my mother had to be a speedster like me, and after I'd spent a few months acting as the Flash, I realised that the man who'd killed my mother was still out there… and he was the man I'd thought of my mentor."

"Really?" the Vision looked at Barry with an almost nonchalant manner, even as the three other Avengers looked at him incredulously. "Why would he do such a thing?"

"Would you believe it if I told you he was from the future and came back in time to destroy me before I could defeat him when I was older?"

"Time travel?" Doctor Banner looked at Barry in surprise. "That's a thing in your universe?"

"Kind of," Barry shrugged. "I'm still working on it, which is another reason why I'm here; I need to get a line between going so fast I travel in time or just going really fast without doing anything too extreme in the process."

"Tricky," Thor noted.

"Yeah," Barry nodded, looking around at the other four men for a moment. "Anyway, I managed to find out about his role in my mom's murder, and set things up so that I was able to get a confession out of him, but then there was a whole thing involving the creation of a new singularity that could have destroyed my city and opened up a bunch of rifts to _another_ Earth."

"Another Earth?" Steve asked.

"It's called the _multi_ verse for a reason, Captain," Doctor Banner noted with a slight smile. "It wouldn't be much of a multiverse if there was only two of them."

"Exactly," Barry smiled, before he became grimmer. "Anyway, there's another speedster in that universe who calls himself Zoom, and… well, basically, he wants to take my speed so save himself."

"Ah," Steve noted.

"You say that this 'Zoom' wishes to take your speed?" the Vision asked. "Could that mean he would be interested in Pietro?"

"Don't… think so," Barry said after a moment's thought. "Like I said, I draw on the Speed Force for my powers; from what I've seen, Pietro's just really fast on his own, but I don't get the feeling he's drawing on anything else when he does that, so there wouldn't be anything for Zoom to steal."

"Good to know," Steve nodded.

"So," Barry smiled, after looking uncertainly between the four men, "now that you'v eheard all that… you want me to stick around?"

"Welcome to the Avengers, Barry Allen," Thor smiled after exchanging glances with the other three Avengers, as he held out a hand to shake Barry's. "It will be a pleasure to have you fighting with us on this day."

"Same," Captain America said, nodding in approval as he got up to shake Barry's hand as well. "Whatever else happens, we're not going to turn down help with something this big."

"Thanks," Barry nodded, standing up and clapping his hands together firmly. "Well then, let's get this all together and show this psycho robot who's boss."

"Amen to that," Steve nodded firmly. "Good to have you on the team, Barry Allen."


	8. Sharing Secrets

Looking around the small plane that the Avengers were using, the team all using this brief moment of respite in preparation for the battle they would face once they landed, Barry wasn't sure if he should consider this cool or intimidating.

His team-ups with Oliver to deal with Rainbow Raider, Captain Boomerang and Vandal Savage had been cool, but they were also relatively small-scale when he got down to it. Savage might have _planned_ to destroy a city, but that was just an incidental detail in terms of his main plans so long as he got to kill Carter and Kendra, and Roy and Digger had been fairly petty in their final goals (and Silver Banshee and Livewire had struck him as fairly small-scale as well, even if they were dangerous enough for Kara to need his help).

This time, he was dealing with someone who was planning to basically destroy a _planet_ just because he was seriously screwed up…

Still, even if he was aware that he was dealing with larger stakes than he'd ever faced before, he was still young enough to focus on the part that found this all cool rather than fret about what else he had to deal with.

"So," Hawkeye looked curiously at the red-clad speedster, "if you're from another universe, what's the super situation like there?"

"Super situation?"

"This world saw no superhuman feats of violence before Mr Stark announced his identity as Iron Man to the world at a press conference seven years ago, and since then the number of enhanced persons has grown significantly, as has the rate of world-ending threats," the Vision noted. "I confess to some curiosity as to what the social situation is like on a world which has developed under different circumstances, since I feel safe assuming that you do not have a Tony Stark to act as such a catalyst on your world?"

"Which is a great loss to it, I'm sure," Tony smiled at Barry.

"Anyway," Doctor Banner noted, shooting an expression at Stark that reminded Barry of the way Caitlin looked at Cisco when he was on one of his strange 'rants' about some science or pop culture topic, acknowledging that he was annoying even as they still cared, "you said that the particle accelerator explosion that gave you your powers was the main catalyst for anyone developing powers in your world, but… does that mean you were your world's _first_ hero?"

"Actually," Barry replied, smiling as he glanced around the jet's interior, "the first major hero on my world- well, the first one like any of you guys- is a guy named Oliver Queen."

"Oliver Queen?" the Black Widow asked.

"He was a billionaire playboy before his family's yacht sank while he was out on a trip with his dad and his… well, his girlfriend's sister," Barry explained, briefly wondering if he should be telling strangers this much about Oliver before pushing the thought aside; they were all heroes together right now. "He ended up stuck on an island for five years-"

"Five _years_?" Tony cut in, looking back at the speedster with a brief smile. "Can't decide if that's better or worse than what I did."

"This man was stuck on an _island_ , Stark; no matter how brilliant or otherwise he might be compared to you, I doubt even you could get off an island the same way that you managed to escape from the Ten Rings," the Black Widow observed.

"Oh, I dunno about that," Tony smiled. "If that was an option, I might've been able to give the first suit's rockets a better boost…"

"Anyway," Barry continued, "from what I heard, he actually ran into a few marooned soldiers and rogue government operatives who helped him learn how to actually cope with everything he was up against, and when he got home, he used the survival skills he'd learned during his time there to start trying to clean up his city."

"Survival skills?" Natasha asked.

"Not only is he the best fighter and tactician I've met, but he's _very_ good with a bow and arrow."

"A billionaire with a bow and arrow?" Rogers asked, looking at Barry in surprise. "So… your world's first hero is basically Stark with Barton's skillset?"

"Huh," Iron Man said, looking at him in surprise before glancing over at Barton. "Wonder what that's like?"

"He… has his problems," Barry admitted; he might admire Oliver, but he wasn't blind to some of the things Oliver did that he would never totally agree with. "He's… done some things that I'm not comfortable with, but he _is_ a good man."

"Done things?" Natasha asked.

"That's not important," Barry said, wishing he hadn't said that much; he wasn't going to tarnish Oliver's reputation in a parallel universe when these people would probably never even meet him. "What matters is that he did his best to save his city from a machine that caused earthquakes in his first year back from the island, defeated an old friend who'd been driven insane by some world war two super-serum in his second year, and took on some ancient group of assassins in his third year; I think he's dealing with some kind of deranged mystic crime boss back home at the moment, but I haven't had the time to really ask him what's going on in detail because I've got my own villain to deal with."

"You handle your problems, he deals with his?" Steve asked.

"Basically," Barry nodded. "I mean, Oliver knows that I'll be available if he asks me, and he and his team understand the same thing goes for me if they need help, but we've both got our own cities to be responsible for most of the time; the last time I asked for his help, we were trying to save a reincarnated Egyptian prince and priestess from this immortal psychopath-"

"Immortal psychopath?" Wanda asked. "What do you mean?"

"I mean that he had been alive since ancient Egypt and spent that time finding this couple who'd been subjected to some kind of system of perpetual reincarnation at the same time as he just became immortal," Barry explained. "There's something about how he became stronger every time he killed them, but personally I think he was just a psycho who couldn't accept that the woman he'd loved had never wanted him and got off on 'punishing' her over and over."

"Immortals and reincarnation as winged warriors?" Rogers looked sceptically at him. "You have a very strange world, Barry."

"Says the guy sitting next to a literal god," Barry noted, indicating Thor before looking more uncertainly at the man with the hammer. "Uh… you _are_ a god, right?"

"Essentially," Thor nodded at Barry. "My people acted as gods to the people of Midgard in the distant past, but these days we remain uninvolved in affairs of this dimension, although I have chosen to involve myself further."

"Cool," Barry nodded.

"Out of curiosity, what is difference between 'alternate dimension' and 'alternate universe?" Wanda asked, looking curiously between Barry and Thor.

"An alternate dimension has various different laws of physics and biology from our world, but alternate universes are basically the same in terms of what kind of creatures and people live there and what it all looks like, but the actual history of everything is… well, it's different," Barry shrugged. "Right now I'm not sure if the difference is just that some people were born in my world who weren't born in this one, or if it all goes back to when that meteor crashed and that immortal I told you about came into existence, but…"

"Yeah, we get it; not really time to carry out that kind of in-depth analysis on what's a purely academic matter," Clint nodded at the speedster.

"And we don't even know if our worlds were always separate or if they diverged at some key moment, and there's no way to be sure if the key moment was something anyone would actually notice," Bruce noted. "It could be something as simple as someone taking a different route during a trip to a Roman market set off a whole new chain of events; when you get down to it, there's no way to know what we're dealing with."

"Trust me, it's complicated to think about even _before_ I seriously think about the fact that somebody changed my history already."

"What?" the Black Widow looked at Barry in surprise. "Someone changed your _history_?"

"And you _know_ about it?" Steve added.

"That was… that thing you told us about, right?" Bruce asked. "You mentioned that your enemy killed your mother when you were a kid because he was angry for what you'd done in the future; did he… change your history after that?"

"I… _think_ so, anyway," Barry nodded. "I mean, he didn't exactly give me a clear rundown of what he'd done to my timeline, but when I spoke to him after I captured him, something about him going into the past and changing history meant that he lost his connection to the dimensional energy source that gave him his speed, so he had to just… take over from the scientist who created the particle accelerator in the original course of events so that he could make it happen earlier… and my dad probably wasn't framed for my mom's murder in the original timeline."

"Yeah…" Bruce nodded thoughtfully at Barry's description for a moment. "Don't know if I told you this earlier, but… I'm sorry you had to see that."

"…You saw it too, didn't you?"

"…Yeah," Bruce nodded, his head bowing slightly, making a concession that he would never have made to someone who didn't have this experience. "My dad beat me pretty much ever since I was born because he was convinced I was going to turn out to be as big a monster as he was, and then he ended up beating my mom to death in front of me when she tried to take me away from him…"

" _Damn_ ," Barry said, wincing as he looked sympathetically at the scientist. "I'm… I'm sorry."

"Just confirmed he was a monster," Bruce said firmly.

"Doesn't mean you're one," Stark noted, looking over at his friend with a new sense of sympathy in his manner.

"We are not the product of our parents," the Vision noted with a brief smile. "After all, I am essentially the child of Ultron."

" _And_ JARVIS," Tony noted at the android. "Don't discount JARVIS."

"The _point_ ," Barry said, "is that our parents just set the stage for what we'll be, but that doesn't mean they're the be-all and end-all of what we are." He smiled reassuringly at the scientist. "From what I've seen of you, you're a good guy, Bruce Banner; don't let yourself get bogged down in what you think you can't be or you'll never get anywhere."

"You think so?"

"Hey, Oliver's parents were involved in a plot to destroy a sizeable part of his home city and he dedicated himself to stopping it as soon as he found out what they were up to," Barry smiled. "Even if I don't always approve of _how_ he gets the job done, I've never questioned that he's a hero."

"And _that_ is something we always need to remember," Steve smiled at his new associate, before he assumed a more serious expression. "We're getting close."

"Yeah…" Stark said, glancing at the displays before him for a moment before looking back at the rest of the team, "I already discussed this with Capsicle and my Science Bro, but it needs re-said; odds are good that we're not going to all make it through this, but we can't leave even one Ultron drone standing or he'll get away no matter what we do."

"And we can't forget that Ultron knows we're coming," Rogers added, looking solemnly around at the rest of the team. "Odds are we'll be riding into heavy fire, and that's what we signed up for. But the people of Sokovia, they didn't. So our priority is getting them out."

"We can spread the word," Pietro nodded, indicating himself and Barry.

"And me," Wanda noted.

"Good call," Steve nodded at the three new people before he continued, solemnly addressing the rest of the team. "All these people want is to live their lives in peace, and that's not going to happen today. But we can do our best to protect them, and we can get the job done, and find out what Ultron's been building. We get to his base, and we clear the field. Keep the fight between us. Ultron thinks we're monsters and we're what's wrong with the world. This isn't just about beating him. It's about whether he's right."

Listening to Steve Rogers at that moment, Barry just wished his world would one day have someone who could make that kind of speech to the heroes. Oliver was great at tactics, and he liked to think he was good with people, but neither of them had the kind of calm personal strength that this man seemed to give out just by standing there.

This wasn't his Earth, and he'd only met these people a matter of hours ago, but he wasn't going to leave this world until he was _sure_ he'd saved it from that psycho robot.


	9. The Rise of Sokovia

As he ran anxiously around the city, Barry was silently amazed at how easily he was settling into his current dynamic with Pietro. He'd spent so long having to fight Thawne/Wells and Zoom- his brief alliance with 'Jay' didn't count as Jay had been apparently powerless at that point- that it was almost strange to find himself racing _alongside_ another person with superspeed. With his suit's radio adjusted to the necessary frequency to keep in touch with the other Avengers- along with a warning to turn off the transmitter when he was just talking to those people immediately next to him if he didn't want things to get confusing- he and Pietro were nipping in and out of the surrounding buildings, getting everyone they could find out of the upper levels and moved to the nearest large open area, leaving the lower levels to evacuate themselves from their homes before fleeing the city.

Barry had to give these people credit; from what he'd read, this whole country had some issues with the Avengers, but they were at least reacting to Pietro's warnings quickly enough. Barry had been given a quick warning in Sokovian that he could yell out when he entered each flat to explain the situation as promptly as possible, but he was sure that he was still attracting a few stares from his mangled pronunciation of it, and Wanda's telepathic instructions were probably helping them get the job done. Thor and the Hulk were dealing with Ultron's main lab while Iron Man and the Vision looked for Ultron, which allowed the Avengers to disperse the rest of their resources fairly evenly as they prepared for the evacuation.

When the drones appeared, Barry only had a moment to curse their luck before he quickly leapt into action, Pietro close behind him as the two of them charged into the wave of drones in front of them. Barry doubted that this kind of strategy would work on whatever Ultron had used to create his latest body, but for the moment, while these drones were powerful, they weren't strong enough for him to need to resort to the Mach Punch so far. He'd used the occasional lightning blast if he was faced with a large quantity of drones in a cluster rather than a semi-straight line, but for the moment, they still had enough control of the situation that he didn't want to risk forcing Ultron's hand by showing too much skill too soon. While Pietro had to focus on taking out the drones, Barry was able to spare a few seconds on some occasions to hit a higher speed and take a quick assessment of the battlefield to be sure that the other Avengers were coping with their assigned tasks, but apart from knocking a few drones off-balance when they came close to the cars Captain America was helping to cross a bridge, even those Avengers with skills rather than powers seemed to be coping with the whole situation rather well.

 _What's Ultron actually planning_? Barry asked himself, knocking one drone off-balance just as it fired its latest energy blast so that the attack would hit one of its fellows rather than its original target. _Unleashing a robot drone army would be difficult, but there's only so many he can let loose before he runs out of manufacturing materials_ …

As the city shook below him, Barry wondered if he was dealing with an earthquake or some kind of subterranean drone, but that thought was cut short when he ran to the edge of the city and realised that he was looking down as the ground beyond the city's limits literally _broke away_ and vanished below them, to say nothing of bridges cracking on either side of him.

He'd faced large-scale disasters before, but there was still a marked difference about Mark Mardon causing a tidal wave and Ultron going to all the effort of creating whatever he'd need to do _this_ (and he wasn't just thinking about the fact that this wasn't a problem he could stop by running to create some kind of counter-wave like Caitlin had suggested before his first time-jump).

"Ultron lifted the entire _city_?" Barry looked at Pietro incredulously.

"It looks that way," Pietro mused, looking back at Barry. "Did anyone do this in your world?"

"Not really," Barry confirmed, looking grimly at the rapidly-receding ground. "I mean, Oliver's first major enemy tried to destroy his city with a machine that generated artificial earthquakes, but that didn't involve lifting it up like this…"

Inwardly, his mind was racing as he considered the implications of what he was witnessing here. Geophysics wasn't something he'd covered extensively, but after the near-tidal wave he'd witnessed on his first time-travel experience, he'd done some research on potential large-scale disasters to get an idea for what his foes might try later, and right now this situation, coupled with Ultron's comments when he was a prisoner, was reminding him of some of the things he'd read about possible consequences of meteor strikes on modern Earth.

 _OK, something this big rising up at this rate… assuming Ultron's got some way to keep everything in one piece until he's_ ready _for it to break…_

Barry didn't remember the exact figures he'd read, and he had no way of working out how heavy this makeshift meteor was even if he did, but that didn't change the fact that this wasn't good.

" _Do you see_?" Ultron's voice suddenly boomed out, as though he was using a loudspeaker. " _The beauty of it, the inevitability. You rise, only to fall. You, Avengers, you are my meteor, my swift and terrible sword and the earth will crack with the weight of your failure. Purge me from your computers, turn my own flesh against me. It means nothing. When the dust settles, the only thing living in this world will be metal_."

"Well," Barry glanced over at Pietro once they were both sure Ultron had finished speaking, "that guy's completely insane."

"Quite," Pietro nodded, before glancing over Barry's shoulder and abruptly charging past him. Turning around, even Barry's enhanced reflexes were only in time to see a series of drones go flying apart as Pietro crashed through them, prompting him to simply shrug and charge down another street to follow his new ally's example.

" _Incoming already came, Stark_ ," Captain America's voice suddenly came over the radio, likely responding to a more private transmission from Iron Man as the sound of something breaking accompanied the radio. " _Stark, you worry about bringing the city back down safely. The rest of us have one job;_ _tear these things apart. You get hurt, hurt 'em back. You get killed, walk it off_."

Barry decided not to over-analyse that particular statement and just focus on the important part of that statement; right now, they had a mass of robot drones under the control of a genocidal psychopath on their way to the city, and the best any of them could do was take down as many as possible until their experts were able to stop Ultron's weapon. Glancing over at Pietro, the two shared a nod before they charged towards the drones, Pietro smashing through them through sheer speed while Barry launched the occasional lightning-bolt to take out a few more. With the immediate wave dealt with, the two speedsters dashed through the city, taking out the occasional drone 'pocket' before they could join their fellows in larger numbers, Barry keeping an eye out for the other Avengers as he ran. He noticed Thor and Steve working together by using the hammer to throw Steve's shield with even greater force than usual, and glimpsed the Hulk tearing several drones apart with his bare hands, but Barry kept on running, only coming to a halt when a drone struck him in the side and sent him into the nearest wall.

"You really think you're accomplishing anything here?" the drone said in Ultron's voice.

"My first week using this suit, I faced a guy who could clone himself," Barry countered, flexing his arms as he got back to his feet while glaring at the drone. "I get that you're building these things, but you're going to run out eventually."

He didn't give Ultron the chance to respond to that, charging through the drone with such force that he saw the head flying up into the sky before he focused his attention back on the road in front of him, soon catching up with Pietro as the other speedster paused at a crossroads.

"Good?" the white-haired young man asked.

"Just Ultron being Ultron," Barry clarified, shaking his head. "What is it about evil robots that they like talking through their minions?"

" _Alright_ ," Clint's voice suddenly reported over the radio before Pietro could answer the question himself. " _We're all clear here_."

" _We are not clear_!" Steve yelled, evidently still fighting drones wherever he was in the city. " _We are very not clear_!"

" _Alright, coming to you_ ," the archer said, before Pietro blurred and Wanda was suddenly standing beside the two speedsters, the young woman immediately deflecting the next wave of approaching drones gathered in front of them and the Sokovian police.

"How are you?" Barry glanced at the young woman.

"I… needed a moment," the telekinetic replied, actually sounding sheepish at that confession before she shot Barry a reassuring smile. "But Barton helped."

"He did?" Pietro asked. "How?"

"He reminded me that we are all lost right now," Wanda replied, wincing as a more intense blast struck her shield even as she kept it up. "What matters is how we cope with it."

"Fair point," Barry smiled. "If it helps, we all get overwhelmed sometimes; I still wonder what I did in my life to reach a point where encountering a telepathic intelligent gorilla is just an odd day rather than the strangest day I've ever had."

"Gorilla?" Pietro asked, only to break out from behind the shield and tear through the approaching drones when the latest barrage forced Wanda to her knees. Deciding that this wasn't the time to share stories, Barry quickly rubbed his hands together and launched another lightning-bolt at their enemies, the attack apparently absorbing energy from the shield as the resulting lightning was crackling red as well as his familiar gold energy.

" _The next wave's gonna hit any minute_ ," Steve's voice suddenly sounded over the team radio link, which at least suggested that the first wave of drones was out of it now. " _What have you got, Stark_?"

" _Well, nothing great_ ," Iron Man responded solemnly. " _Maybe a way to blow up the city. That'll keep it from impacting the surface if you guys can get clear_."

" _I asked for a solution, not an escape plan_ ," Steve countered.

" _Impact radius is getting bigger every second_ ," Iron Man reaffirmed. " _We're going to have to make a choice_."

"What choice?" Wanda looked over at Barry as the radio connection ended.

"Let Ultron's plan finish so this thing will destroy the world when it drops or blow it up now so we can limit the damage it'll do when it goes down," Barry said grimly.

"Ah," the Sokovian woman said.

"Even when we're _on_ it?" Pietro asked.

All Barry could bring himself to do in response was look silently back at Pietro, not wanting to actually tell the first genuinely good fellow speedster he'd ever met that they would have to die to save the world.

" _Cap, these people are going nowhere_ ," Natasha said; Barry wasn't sure if the Widow was aware that she was still on an active radio frequency, but he supposed he couldn't criticise her ignorance when he hadn't known that either. " _If Stark finds a way to blow this rock_ -"

"Not 'til everyone's safe," Steve cut her off firmly.

"Everyone up here versus everyone down there?" Natasha countered. "There's no math there."

" _I'm not leaving this rock with one civilian on it_ ," Steve said firmly.

" _I didn't say we should leave_ ," the apparent ex-assassin said; at this point, Barry wasn't sure if she was even aware that the radio was still on or not. " _There's worse ways to go. Where else am I gonna get a view like this_?"

Looking over at the Maximoff twins, Barry didn't know if he should be proud or sad that they were so accepting of that decision; they were barely out of their teens, and neither of them showed any signs of anger or panic when the team they'd considered the enemy just a few days ago basically pronounced a death sentence on all ten of them to stop a literally apocalyptic threat.

" _Glad you like the view, Romanoff_ ," an unfamiliar voice suddenly cut in over the radio. " _It's about to get better_."

Exchanging a glance with Pietro, Barry and his fellow speedster immediately ran to the edge of the city and ran around it until they reached the area where Steve and Natasha were standing. Turning around to look at the view they'd been discussing, Barry soon found himself speechless as he took in the incredible sight of a flying aircraft carrier, with vast propellers on its sides, flying alongside the rising city.

" _Nice, right_?" the new voice said. " _I pulled her out of mothballs with a couple of old friends. She's dusty, but she'll do_."

"Fury, you son of a bitch," Steve said, smiling as he stared at the new arrival.

" _Oooh_!" the new speaker said in the teasing manner of a man who rarely made actual jokes. " _You kiss your mother with that mouth_?"

" _Altitude is eighteen thousand and climbing_ ," a new woman said.

" _Lifeboats secure to deploy_ ," another new male voice said, reinforcing Barry's theory that these new speakers were on that carrier. " _Disengage in three, two… take 'em out_."

With those words, hatches opened in the bottom of the carrier- the parts that would have been underwater if this thing had been the boat it looked like- revealing a series of large, open-topped vehicles that put Barry in mind of those troop transports he'd seen from news footage of D-Day. They were moving at an almost leisurely pace compared to some aircraft Barry had seen over the years, but they were clearly heading for the edge of the city, settling into a position near the areas where the ground had come through the tremors of their ascent comparatively intact.

"This is SHIELD?" Pietro asked (Barry took a moment, but if he remembered those articles he'd skimmed while researching the Avengers, SHIELD had been this international spy agency that brought the Avengers together before it was revealed that some of the higher-ups had been working with a Nazi splinter group or something).

"This is what SHIELD's supposed to be," Steve replied with a cool certainty.

"This is not so bad," Pietro acknowledged.

"Not bad?" Barry looked at Pietro incredulously. "These guys have a flying aircraft carrier; that is… _awesome_!"

"Good way to keep everything mobile," Natasha explained, smiling slightly at his enthusiasm.

"Let's load 'em up," Steve said, looking over at the speedsters in a manner that made his point clear.

"Right," Barry nodded, turning around to dive back into the city; the sooner they could evacuate the civilians, the sooner they could focus on blowing this city to pieces before Ultron could drop it.


	10. Final Stand on Sokovia

Whenever he looked back on the events of his first collaboration with the Avengers, Barry wasn't sure if he had preferred fighting the drones or guiding the people to the 'lifeboats'. Fighting the drones had the advantage of being simple, as all he had to do was find the metal men and smash them, but even if guiding people to the lifeboats had been more difficult, he could appreciate the idea that he was actually able to save someone rather than destroying stuff.

While Clint, Natasha and Steve moved to lead various groups to the boats as Wanda held back any attacking drones with new barriers, that left Barry and Pietro to dash back and forth gathering up any random stragglers, hurrying them to the nearest suitable 'lifeboat'. Looking up, Barry noticed Iron Man flying through the skies and taking out various other drones, accompanied by what looked like a gunmetal-grey version of his armour with a large gun on one shoulder.

 _Looks cool, but I can't do anything about what's going on up there, so I'll focus on fixing things down here_.

"Going well?" Wanda smiled, as Barry came to a halt near where the Maximoff siblings had chosen to make their latest stand against the current drone wave.

"As well as you'd think," Barry clarified, before looking over at Pietro. "You and I need to focus on getting the remaining civilians onto that lifeboat; if we can clear things now, it's easier for everyone else later."

"Not much space on these ones," Pietro noted with a glance.

"Then we load 'em up now and they can come back for more later," Barry said firmly. "Let's go."

With that instruction, the Maximoffs and Barry dashed into the heart of the city, Barry and Pietro alternating between taking out drones and carrying civilians back to the lifeboats while Wanda took up a position that helped her defend herself and the rest of the team from further drone attacks. Over this range, Wanda's shields couldn't do more than deflect Ultron's drone onslaught, but that was enough for her teammates to be warned of further attacks and deliver their own retaliatory strikes accordingly.

 _We can do this_ , Barry thought, allowing himself to hope as he smashed through three drones and carried four toddlers (let their parents have just lost track of them in a panic) to safety practically simultaneously. _We've got Ultron on the ropes… Iron Man can get this thing down safety… we're_ winning…

" _Avengers_!" Iron Man's voice suddenly called over the radio-link. " _Time to work for a living; rendezvous at the central church_!"

Taking a moment to make sure that he'd moved the immediate civilians to safety and there was no obvious sign of drones coming towards them, Barry ran for the indicated church, a quick glance to the side confirming that Pietro was following him with Wanda.

By the time they reached the centre of the floating island the city had become, Thor, the Vision, Iron Man, Hawkeye and Captain America had already taken up position inside an old church, its windows gone and rubble lying all around its interior as the Avengers fended off the first wave of drones attacking them here. Barry briefly heard Iron Man send a message to Black Widow and the Hulk as he took a quick run to throw the last of the attacking drones into an old sewer, but by the time he got back to the church the black-clad female Avenger had joined the others, Natasha giving him a brief nod before she looked back at the man in red armour.

"What's the drill?" she asked.

" _This is the drill_ ," Iron Man replied, indicating the strange cylinder in the centre of the church. " _If Ultron gets a hand on the core, we lose_."

"What does it do?" Wanda asked.

" _Drops this city with the force of a meteor to trigger an extinction-level event once it's high enough above the ground_."

"Ah," Barry glanced over at the machine again. "So, keep him away from that thing; good to know."

"Good to know?"

"Always makes it easier to have a simple goal to focus on," Barry clarified for Wanda, before he looked thoughtfully at Iron Man. "Just to check, I can guess that blowing this thing up probably isn't a good idea, but is there a reason Pietro and I couldn't just take it apart really fast?"

" _Ultron knows about you both and could have designed this thing to self-destruct if something like that happens, which could cause the kind of blast we're trying to stop_."

"Good point; just wanted to be sure we weren't overlooking the obvious."

"So how do we do this?" Natasha asked, just before a sound from outside the former church drew the team's attention, turning around in to see the Hulk literally landed on one of the last drones standing before throwing the other aside. The large green figure entered the church to join the rest of the Avengers just before Ultron appeared, floating several feet in the air above a street as he looked dispassionately at the church.

"Is that the best you can do?" Thor yelled angrily at Ultron. In response, the robot raised his left hand, and suddenly a mass of new drones had gathered around him, running down the street and from the surrounding buildings like children hurrying to meet Santa.

"You had to ask," Steve noted, glancing grimly at the Asgardian warrior.

" _This_ is the best I can do," Ultron proclaimed, looking at the assembled heroes with what Barry would have called a mocking expression if their enemy wasn't a robot with fixed facial features. "This is exactly what I wanted; all of you, against all of me. How could you possibly hope to stop me?"

Exchanging glances with the other Avengers, Barry saw the same determination in their eyes that he felt right at that moment; he might be up against some stiff odds, but he was never going to give up and let Ultron destroy even an alternate Earth if there was anything he could do to stop it.

" _Like the old man said_ ," Iron Man spoke up for the gathered heroes, glancing back at Steve before turning to face Ultron again. " _Together_."

As though those words had been a cue, the drone army charged towards the Avengers, all of whom leapt into action themselves. The Hulk's battle-cry was almost a signal for the team as the drones advanced in, the human Avengers drawing their weapons while the superhumans engaged the drones in more direct combat. Dashing around the church try and knock back any drones that came in through the shattered windows and fragile walls, Barry could see others entering the church from the roof, but also saw Wanda throwing drones into the air with her powers, Captain America leaping over another in a spinning jump that sent it crashing into one of its fellows, the Vision literally punching _through_ his own opponents, an intense lighting-burst from Thor's hammer shattering those drones around him as he tore out the 'spine' of the nearest one, Iron Man saving Wanda from a drone she missed while launching a series of repulsor blasts, Pietro practically acting as Barry's reflection as he ran along the other side of the churchBlack Widow shooting a drone in the face while Hulk literally bit the head off another…

The sound of Ultron's voice in the air prompted Barry to glance up, but a moment was all he needed to see that the Vision had it under control. Ultron's would-have-been body recovering from being thrown into a wall to send a powerful burst of yellow energy from his forehead to blast his creator out of the church before Ultron could even touch the ground, Thor and Iron Man swiftly joining the Vision in his assault on Ultron with their own energy blasts. The sight was so impressive that Barry paused in his race around the buildings to witness what was happening to Ultron, simultaneously charging a lightning-bolt in case it was needed.

When the energy died down, Barry was relieved to see that it had at least made some kind of impact; Ultron might still be standing, but his body had clearly been damaged by the assault, with his face in particular looking partly melted.

"You know, with the benefit of hindsight-" Ultron began, before the Hulk charged forwards and slammed his fists directly into their enemy, sending the large robot flying backwards once more. Still clearly enraged, the Hulk turned to roar at the remaining drones, which turned around and began to run or fly away as the green goliath gave chase.

"They'll try to leave the city," Thor noted.

" _We can't let 'em; not one_ ," Stark said firmly, flying upwards with the Vision close behind him, the two airborne Avengers swiftly joined by the figure in grey armour Barry had seen earlier.

"We've gotta move out," Steve glanced around the shattered church at the rest of the team.

"Even I can tell the air is getting thin. You guys get to the boats; I'll sweep for stragglers-"

" _We'll_ sweep for stragglers," Barry corrected, stepping forward to look firmly at the man in blue. "I get that you're the leader and have to take responsibility for everything, but Pietro and I can do this faster than anyone; you really think you can't use our help?"

"Appreciated," Steve nodded at Barry.

"What about the core?" Clint asked.

"I'll protect it," Wanda said, glancing over at the archer in a manner that made it clear her words meant something more than the obvious. "It's my job."

"And speaking of jobs…" Barry said, placing a hand on Pietro's arm and rapidly vibrating his body while focusing it into his hands; he couldn't be sure if this would work, but with Pietro's body already adapted for superspeed, and aware of the sensation of losing speed after Harry's earlier 'trap', this _should_ be possible… he was reaching out to the other man… he felt as though he'd been struck by lightning all over again and was still letting it _out_ of his body… he felt a slight fatigue even as he was sure Pietro's speed was being increased…

" _Whoa_!" Pietro yelled, moving away from him only to pause as he noticed the lightning crackling around his hands. "What did you just do?"

"Gave you a boost," Barry smiled.

"A boost?" Clint looked between the two speedsters in surprise. "You can do that? Boost his powers?"

"A couple of my enemies have managed to take my speed from me against my will in small doses, so I thought it was worth a shot to see if I could give him a willing boost, anyway," Barry shrugged. "I wouldn't like doing it to someone who didn't have speed like mine already, and it might not even work, but it can't hurt him and I figured we could use an extra edge this close to the endgame."

"Thanks," Pietro said, before he looked at Wanda. "You're sure-"

"I can handle this," Wanda said, hurling another red blast at an approaching drone before glaring at her brother as the three 'normal' Avengers hurried off back into the city. "Get the people on the boats; you or Barry can come back for me when everyone else is off, understand?"

"You know, I'm twelve minutes older than you," Pietro pointed out with a smile.

"Go," Wanda said firmly to her brother, before glancing over at Barry. "I have this; be a hero."

"Be _Avengers_ ," Barry countered, even as he accepted Wanda's point. "And that's all of us now we're on this team, Wanda."

As he turned to run down another street, he supposed that this was the best thing he could do right now. As the last dash started, it took him a few moments before he realised that he was staying close to Pietro, as though he was subconsciously making sure he hadn't made a mistake with his earlier actions, but it soon became clear that the young man was coping well with his new speed boost, drones flying apart with greater ease than they had in the earlier fight.

 _Call me cocky_ , Barry reflected with a grin as he vibrated through a couple of drones to knock them into a nearby wall, _but I think we can really do this…_

As he approached the area where the lifeboats were taking on the last group of passengers, Barry was about to move on when he noticed Steve, Thor, and Clint already in this area, but a glance to the side revealed that Natasha was talking with the Hulk in a small park just visible between the ruins of a previously shattered building, slowly walking up to the green giant with a certain… he wasn't sure he could get away with saying 'tenderness' about a woman who gave the impression she could beat up even Killer Frost on top of all the women on Oliver's team back home…

Then he saw the Quinjet they'd used earlier flying over the rising city, firing a spree of bullets at such a speed even he had trouble seeing them, and Barry immediately leapt into action. His thoughts shifting to high speed, Barry realised that he still had a couple of seconds before those bullets reached any of the Avengers, prompting him to run for the highest reasonably-stable-looking building and move up the side of it as quickly as possible. Once he reached the top, Barry ran over the roof and leapt off, praying that his mental calculations had been correct as he dived towards the Quinjet; if he was wrong, he'd need to create an updraft _really_ fast…

As he came up to the Quinjet, Barry instinctively started vibrating, phasing his way through the hull of the ship to crash into the robot in the pilot's seat, knocking Ultron out of the chair before even his accelerated computer brain could react to the attack. As Ultron got back to his feet, Barry lashed out with a new lightning bolt, blasting Ultron out of the ship and hurtling towards the ground.

"Hey, guys!" he yelled, quickly activating his helmet's radio once again. "Ultron's heading for the ground after taking several thousand volts to the chest, and I'm in the jet without any idea how to fly the thing; any ideas?"

" _Just turn it around so it's not going to crash into anything; someone'll be there to get you out in a moment_!" Steve replied.

"Check!" Barry nodded, turning back to the pilot's chair and making a quick assessment of the controls; he still wasn't comfortable trying to put this thing in for a landing, but if the handles were how this thing was meant to be steered, he should be able to obey Steve's instructions. Taking a grip of the handles, he turned the ship around so that it was pointing away from the city, heading for the mountains off in the distance. The sound of something hitting the floor prompted him to turn back in case Ultron or a drone had attacked, but while it was a tall grey figure he didn't recognise, the closer resemblance to Iron Man made it clear that he wasn't dealing with another drone.

" _Flash_?" the figure said, helmet raising up to reveal a dark-skinned face with a nonchalant smile.

"That's me," Barry nodded. "You're with the Avengers?"

"Call me War Machine," the man said, indicating the door behind him. "Think it's time for us to vacate the premises."

"I'm all for that, believe me," Barry smiled, walking over to join the man in armour, who slung an arm over Barry's shoulders and flew out of the jet towards the helicarrier. Barry was about to protest at this move, but a quick glance confirmed that there were no 'lifeboats' hovering on the edge of the city and he could see the Hulk, Steve, Natasha, Pietro and Clint standing on the deck of the helicarrier, which leant weight to the idea that there were no other civilians left in the city. As War Machine landed on the helicarrier, Barry stepped away before the armoured man flew back into the air, leaving Barry to glance around at the rest of the team.

"Everyone OK?"

"Getting there," Steve replied with a grim smile. "We've got everyone out of the buildings, and Vision's gone to get Wanda; Thor and Tony are just about to-"

The question of what the other two Avengers were going to do was swiftly answered when there was a loud noise that resembled an explosion and an earthquake, briefly making Barry flash back to that dark moment when Vandal Savage had destroyed the city before he took his second twenty-four-hour jump back before he registered that the city was breaking up in the sky rather than immediately hurtling to the ground.

"That's… good, right?" he glanced over at the rest of the team.

"From what Stark said, anyway," Natasha nodded, the rest of the Avengers joining Barry on the edge of the helicarrier to watch the city break apart in front of them. "If it had gone back down while in one piece, it would have been the equivalent of a meteor strike, but as it is…"

"Bad for these people, but the world keeps going?" Pietro suggested.

"Good a way as any to put it," Steve nodded, before looking solemnly at Pietro. "I can't speak for Stark, obviously, but I can promise you that I'll do what I can to be sure that he'll do what he can to compensate everyone who suffered because of this."

"Everyone?" Barry looked at Steve in surprise. "Is that possible?"

"Stark is _very_ rich," Clint smiled briefly.

"Ah," Barry said, deciding not to question that as he glanced back at the shattering city, now glimpsing a figure in a red cloak flying through the rubble while a gold-and-red figure followed it, Barry quickly identifying the two as Thor being followed by the Vision carrying Wanda.

" _OK, guys_!" Tony called out over the radio, sounding like wind was whistling around him as he spoke. " _We've raining rocks down here, but I think I'm safe saying we're out of danger down here; everyone good up there_?"

"We're fine, Stark," Steve said, looking over at the other assembled heroes as Thor and Wanda joined them, Vision shooting them a briefly apologetic look before he flew off once again.

"Where-?" Wanda began.

"Personal business," Barry said, recognising the grim expression on the android's face from his own experience working with Oliver during that mess with the League of Assassins. On one level, he felt slightly hurt that the Vision was going off to finish something this big by himself, but on the other hand, he appreciated that there were personal factors about the Vision's interaction with Ultron that he didn't know enough to understand.

 _Been the most devastating experience I've faced since I started in this business_ , Barry mused, looking down at the shattered city below them, _but at least we got through this without losing anybody on our side, and we managed to stop civilian casualties in the process_.

Once the Avengers were all back on the ground, he'd make sure everything was in order, but then it was time for him to get home.


	11. Return to Earth-One

"You're turning a storage facility into your new base?" Barry asked, looking at the large building in surprise. The rest of the Avengers had been fully aware that he intended to go back to his world once the current threat of Ultron had been dealt with, and each of them understood why he wanted to go back, but they'd insisted that he stick around to see what they had planned for the future after everything he'd done to ensure that they'd have one in the first place.

"Hey; it gets the job done space-wise, and it has the advantage of being out of the public eye," Stark shrugged.

"That is important?" Pietro asked.

"We got lucky when we managed to drive Ultron out of the tower before he decided to start attacking the wider area," the industrialist said grimly. "I'm not going to leave this team in a position where anyone else trying to attack us has an obvious target to keep us busy."

"Makes sense," Barry nodded. "Oliver and I have to protect our cities back on my world, but Oliver's always managed to keep his base secret from everyone but the enemies who were more focused on him, and my team keeps our base just far enough outside of the main city so that anybody who knows about me doesn't have any immediate civilian hostages to use if they attack us that way."

"Disadvantage of being local rather than global, huh?" Hawkeye noted.

"It's all got its ups and downs," Barry shrugged, before turning to address the Avengers as a whole. "Seriously, though, it's been good to work with all of you."

"Same," Steve said, smiling as he shook the Scarlet Speedster's hand. "It's been an unconventional experience, but if there's a multiverse out there, it's good to know it has heroes like you to defend it."

"Indeed," Thor nodded, as he followed his leader's example to shake Barry's hand. "You are a noble warrior and a valued ally, Barry Allen; it has been good to work with you in this fight."

"Only regret is that we didn't get to meet more of your guys," Clint noted with a brief smile while repeating his teammates' actions. "Wonder how I'd match up to this Oliver guy."

"Getting competitive?"

"Nothing wrong with that."

"Just didn't expect it of you," Tony shrugged with a teasing smile.

"Who knows what would have happened without you here?" Wanda smiled, reaching over to give Barry a hug as Pietro smiled at his friend.

"Eh, you'd have realised the truth about that psycho robot soon enough," Barry shrugged.

"But you ensured that they realised it before they made more than one great mistake," the Vision noted, a slight smile on his face as he looked at Barry. "Your presence has been a most unique addition to this team, Barry Allen, but one we have all appreciated."

"Yeah," Bruce confirmed, walking forward to shake the speedster's hand, an awkward smile on his face. "It's been… well, like the Vision said, it's been unique, but you've given us a lot to think about."

"Just like you've all given me a few things to think about back home," Barry replied. "I mean, I spent so long being my world's first real hero with powers, and I've only had a couple of actual team-ups with Oliver when things were particularly bad, and now I've seen how heroes _can_ be when they're working together…"

"We have our issues-"

"But you're working on them," Barry smiled at Wanda. "You've made a commitment to be the team that you'll work together to make the world better; that's the important thing."

"OK," Tony said, after the assembled Avengers had spent a few moments standing around in silence. "Now that we've got the emotional sentimentality and heroic congratulations out of the way, shall we just get Barry here back home before this gets too sweet?"

"OK," Pietro said, shaking his head at Tony's antics as he took up position alongside Barry, standing at the end of the largest open area in the field around the new Avengers compound. "How do we do this?"

"We start running, and when I run in front of you, you give me one quick shove and I get the last little boost I need to get back to my own universe," Barry replied. "You ready?"

"Ready," Pietro smiled.

"We'll miss you, Barry," Wanda said solemnly.

"Just remember," Clint added with a grin. "If you ever need our help, you're always an Avenger."

"Thanks," Barry replied, as he placed the tachyon device back on his chest and took up his position alongside Pietro.

Working with these heroes had been an incredible experience, no matter how terrifying it was to face something like Ultron, but in the end, his place was on his Earth.

After taking a moment to pace themselves, the two speedsters leapt into action, charging along the field, energy crackling around Barry and Pietro before Barry moved into position in front of Pietro, the race continuing for another moment before something shoved him in the back. Back in the dimensional breach, he registered a group of people in black leather standing around a large metal room, and a flash of a man in black duelling with a woman in similar attire using blue swords of some kind, before some sense prompted him to slow down just enough…

The distortion effect gone, Barry found himself back on the same street in Central City that he had been on when he originally ran into Kara's world. Quickly falling back into his original pace, Barry took a moment to re-orientate himself and then ran back to S.T.A.R. Labs, through the gate and into the main building in less time than it would take virtually everyone else just to cross the street he'd arrived on.

As he dashed back into the observation room of S.T.A.R. Labs, Barry smiled as soon as he saw his original team sitting at their usual array of computers; working with Kara and the Avengers in the field had been fun, but there was something to be said about the idea of getting the old guard back together, even if he'd only been away for a week.

"I'm back…" he said, removing his cowl and looking around at Caitlin, Iris and Cisco, all of whom were looking remarkably nonchalant at the sight of a man who from their perspective should have been missing for over a week. "How long was I gone?"

"Let's put it this way," Cisco said, walking out from behind the console with a broad grin, "you just _annihilated_ your old record."

"You went four times faster than you have ever been," Caitlin confirmed.

"Four times?" Barry repeated, trying to mentally adjust to compensate for this revelation; if people thought this was still the day of the original tachyon trial- God, it sounded like they all thought he was still taking part in the trial- he must have… pulled a Narnia or something and come back to his world pretty much the moment he left it…

Then Harry Wells came in to confirm that his current speed was greater than Zoom's, and Barry forgot all about that particular issue; right now, his time with Kara and the Avengers was just a pleasant memory, whereas Zoom was a clear and immediate threat that had to be stopped ASAP.


	12. Planning for the Race

**Notes for the Chapter:**

> This chapter marks a jump forward to the beginning of 'The Race of His Life'; everything that happened between Barry's return to his world and this episode was essentially the same as in canon, but from here on, I felt that Barry's experiences with the Avengers would have a significant impact on how he responded to Zoom trying to attack him on such a personal level.

As Henry Allen fell to the floor in front of him, Barry fought down the urge to scream as he lost his last parent in a manner that was only slightly less abrupt than the manner in which he'd lost his mother.

Ever since he'd returned from the Avengers' world, despite his various lessons and the insight he'd gained from his time with such distinctive heroes, he felt like he'd been racing to keep up with everything Zoom had thrown at him. He'd thought that he had been able to turn the tables on the other-dimensional speedster after he learned the man's real name, but when that had led to Zoom threatening Wally and capturing Caitlin, Barry had hated the way his enemy had left him with no other option but to sacrifice his speed to have any hope of keeping his allies safe. He'd tried to make himself feel useful with Cisco's hologram trick, but he'd known from the beginning that was only a temporary solution if he was going to keep up his role of protecting the city, which was the main reason he'd gone along with Harry's plan to trigger a new dark matter event and restore his powers.

His experience in the Speed Force had been a strange one, but it had been strangely refreshing to see his mother again, even if he'd known that it wasn't _her_ , and he had naturally revelled in the restoration of his powers and the subsequent defeat of Zoom's army, no matter how disturbing it had been to find himself facing an evil version of Laurel Lance. The team had been forced to reopen the pipeline to keep a few people contained, despite the official metahuman wing at Iron Heights, as they didn't want to deal with the complications of explaining the existence of various doppelgangers to the general population, as well as locking up Black Siren to avoid any hint that Laurel's legacy in this world would be tainted by the actions of her counterpart.

For a few moments, with his enemy's resources stripped down to Zoom alone, he'd really hoped that would be enough…

Then Zoom had come charging into his house, grabbed his dad, taken him away to his old house, waited for Barry to catch up, and broken Henry Allen's neck just because he could.

As he knelt on the floor, holding his father's corpse, Barry couldn't believe that it had come to this; he'd tried so hard to clear his father's name, and Henry Allen had barely even managed to spend a year on the outside before it came to an end…

"I told you family was a weakness," Zolomon said, his mocking tone breaking through Barry's grief as he stood over his rival and his latest victim. "You feel the anger, don't you, Flash? And now the two of us are the same."

If Zolomon's voice had broken into his grief, that grim statement solidified Barry's own resolve.

"No," he said, standing up to face his enemy.

"What?" Zolomon said, looking at Barry in surprise.

"We're _not_ the same," Barry countered, his mind clearer with every word he spoke as he glared at Zoom. "How can you even _think_ that with a straight face? _You_ killed your _own_ dad because he was a twisted monster who beat your mother to death for no reason because he could; you actually _wanted_ him to die for something you _knew_ he did, but I spent years _knowing_ my dad never did _anything_ to my mother!"

"The pain is still real-!"

"And thanks for proving my point," Barry cut Thawne off, still glaring at the Earth-Two speedster. "Dress it up all you like, but in the end, you and Thawne both killed _my_ parents because… because you can't accept the idea that you're both utterly _pathetic_!"

"Pathetic?" Zolomon countered, looking at Barry in momentary surprise before he collected himself. "Bold of you to try projecting, Flash-"

"No, I'm not projecting; you're just pathetic!" Barry countered, forcing himself to ignore his father's body as he glared at Zoom. "Thawne had this whole sick _thing_ about wanting to be me even if he knew he'd never do it, and your dad _literally_ killed your mom right in front of you before either of you even had powers! There's probably all kinds of crap in Thawne's history I don't know about, but for you, even if I can understand that you saw something terrible, everyone else knew who'd done it, you _knew_ that he was the monster everyone said he was, and the way you deal with that is to lash out at everyone else because you can't cope with being that angry? What's the _point_ in anything you've done since then? To be the best? You've just got some warped need to prove you're strong, and you don't even realise that you're proving you're _pathetic_!"

"I am the most powerful speedster in the multiverse-!" Zolomon began.

"Maybe you're fast, but just because you're powerful doesn't mean you're the _most_ powerful, and it _definitely_ doesn't mean you need to smash everything else that just might be a threat," Barry cut Zolomon off; he probably wouldn't be able to get through this guy's twisted psychology, but that wouldn't stop him trying. "I met a guy who went through basically the exact same experience you did, and actually has _less_ control over what he does with his powers than you do, but I'd pick him as the strong one out of the two of you because he's never let his mother's death define him like you have."

"I do not define myself by-"

"Don't kid yourself; of _course_ you define yourself by it! You lost your mom, your dad was a psycho, and suddenly the only thing you can do is prove that he's not the biggest psycho on the block by becoming something worse? You don't even have the nerve to admit that you want to be something more than that; at least _part_ of you must have wanted to be the hero if you were able to trick us like that while you were pretending to be Jay Garrick, and you still didn't take the chance to be better?"

"Being like you is 'better'?" Zoom countered, apparently regaining control of himself as he looked at Barry with new intensity. "You commit yourself to a pointless struggle that will never end, whereas I am pure _power_ in my world-"

"And it's not enough for you," Barry cut him off. "Seriously, have you even looked at what you've been doing lately? You abducted Caitlin from her home, kill her counterpart right in front of her, talk about destroying the city, and you honestly think that she could still feel _anything_ for you when the only thing she was ever attracted to was who you were pretending to be? Any idiot can go out there and break stuff, but it takes _effort_ to actually do something _worthwhile_ -!"

As Zoom charged towards Barry, the Flash only just had time to pull his cowl back over his head before he started to lash out in response to Zoom's attacks. For a moment, the two men were a blur as they traded punches while running deeper into the city, until Barry pinned Zolomon to a wall.

"Go on, Barry," Zolomon said coldly. "Embrace your anger. End me."

Looking at Zolomon's face in that moment, Barry took a moment before he stepped back, glaring at the man.

"What are you?"

"What?"

"You're too egocentric to let yourself die like this; why would you _ask_ me to kill you unless it's a trap?"

Zolomon was prevented from answering when a hand was suddenly thrust through his chest from behind, the body falling away to reveal another Zolomon standing behind him, looking pityingly at Barry.

"And you were so close to it…" the twisted speedster said mockingly.

"If you think that, you'll never understand how wrong you are," Barry countered, fighting down the urge to show how unnerved he was at the image of a man killing himself. "Yeah, you're twisted enough to kill yourself, but what the hell are you going to do now?"

"You'll see soon enough," Zoom said, chuckling at Barry. "I'll give you a few days to grieve, but once you're back at your peak…"

He shrugged and ran away, leaving Barry to glare after his nemesis.

He didn't know what his enemy was talking about, or what Zoom had planned, but he had a feeling that this wasn't going to be pleasant.

* * *

"Zoom wants to race you?" Jesse asked, the team gathered around Barry in the S.T.A.R. Labs control room as they looked sceptically at each other.  
  
"He's obsessed with being the best," Barry noted, privately reflecting on how pathetic that idea was. Pietro might have envied his apparently greater speed when the two men fought with the Avengers, but the younger man had never shown any sign that he wanted to beat Barry in a competition, never mind going to these kind of lengths to ensure such a race would happen.  
  
"Why would we trust him?" Iris asked.  
  
"He just wants to race," Cisco noted reflectively. "You know, it actually makes sense… in a completely off-your-rocker sort of way."  
  
"That can't be everything he wants," Joe said firmly.  
  
"It isn't," Harry put in, still looking at a computer screen from the main monitoring station behind the rest of the team. "This Magnetar that's being developed by Mercury Labs? Turns out, it can act as a pulsar."  
  
"Whoa," Cisco said, looking at Harry with awed apprehension.  
  
"What is a pulsar?" Iris asked.  
  
"It's a power amplifier with a highly magnetized, dense rotating core that can be easily weaponized," Harry explained, pulling up a quick demonstration on a suitable screen.  
  
"Nah, that's not dangerous at all," Iris mused grimly.  
  
"That's what happens to Earth-2," Cisco put in. "What happens in my vibes is because of this machine."  
  
"That thing is powerful enough to destroy a planet?" Iris asked, turning back to Harry while pointing at the screen.  
  
"A lot more than just a planet, if it has the right power source," Harry noted grimly.  
  
"Like what?" Jesse asked.  
  
"Like me," Barry answered, realisation dawning. "That's why he wants to race. He wants to siphon the energy I create when I run."  
  
"He wants to siphon the energy off both of you," Harry corrected.  
  
"When Jay captured me, he said that he used to measure his success by counting the number of victims he had, but now he was gonna measure it by… counting the number of Earths he conquered instead," Caitlin put in.  
  
"He doesn't want to just destroy Earth-2," Harry continued, a grim sense of horror to his tone as he looked at Caitlin. "He wants to take out every other planet in the multiverse."  
  
"How many are there?"  
  
"Infinite."  
  
"Can he do that?" Jesse asked her father.  
  
"If he can create a breach to Earth-2 all on his own…" Joe began.  
  
"He can get to all of 'em," Barry finished, mind flashing to horrific images of Kara or the Avengers, suddenly forced to watch as their worlds were destroyed by something they didn't understand the cause of and with even less idea of how to stop it.  
  
"One pulse to destroy them all…" Cisco mused, stroking his chin as he stared at Harry's computer in horror.  
  
"Right," Barry said, nodding firmly at that information.  
  
He wasn't a hundred percent certain he could duplicate that accident again, but if he could give himself enough of a boost with the tachyon generator, and kept his mind focused on retracing that particularly longer route back to the third alternate Earth he'd visited in the last few weeks…  
  
"I have a plan," he looked at his friends.  
  
"Please say it doesn't involve racing him," Joe said earnestly.  
  
"Yes and no."  
  
"Yes and no?" Caitlin repeated uncertainly.  
  
"I'm going to race him, all right; I just won't be racing him on _his_ terms," Barry clarified with a grim smile. "We can't not race him in case he kills somebody else to try and provoke me again, and I get that I can't just hope I'll beat him in a race before we charge this thing up to the point where it will do what he wants, but if I can just have a couple of hours to spare…"  
  
"What?" Cisco looked at his friend in confusion, Barry looking between Harry and Cisco for a few moments before he came to a decision.  
  
"You're coming with me," he said, looking firmly at the Earth-Two version of a man they'd technically never met.  
  
"Am I?" Harry asked. "To where?"  
  
"To what I'm going to call 'Earth-A'," Barry replied. "If we're going to race for the fate of the multiverse, I think Zoom should have a chance to prove himself against a speedster from _another_ world out there…"


	13. The Battle of the Magnetizer

Standing in the open area of the large abandoned power plant where he had set up the modified Magnetar, the man once known only as Hunter Zolomon was almost disappointed at how easily 'Team Flash' had given up trying to stop him.

It wasn't as if they'd have ever had any real chance at preventing him from achieving his final destiny, of course, but it would have been amusing to see what the rest of them would have tried to come up with to stop this race. He'd tried to sneak around S.T.A.R. Labs as quietly as possible, hoping for some sign of them trying to stick Barry in a cell to keep him away from the Magnetar, and he'd expected them to try something on their own that would allow him to show just how far ahead of them he really was, but they just seemed to be anxiously pacing around as they waited for something, and he hadn't even seen any sign of Allen preparing for their upcoming race.

It wasn't that he objected to having an easy showdown, but he really had been hoping that he'd have the chance to taunt Barry a bit more; Joe West could have been an interesting last-minute hostage…

"Brought the whole crew with you?" he said, mockingly addressing his enemies. "Can't say I blame you; it's gonna be one hell of a show."

"Cut the crap," Wells said, aiming a weapon at him even as he knew how pointless that act would have to be. "We know you plan to power up the Magnetar so you can destroy the multiverse."

"Bravo," Zoom chuckled. "You figured it out, almost; I don't want to destroy all of it. This Earth is at the centre of the multiverse; it's the access point to every other Earth in existence. One trans-dimensional shockwave, and poof."

"Leaving just our Earth," Cisco said grimly. "How generous of you."

"Need to have some place to hang my cowl," Zoom smiled; they might hate what he was planning to do, but that just made it all the more satisfactory to force them to realise that they could do nothing to stop his plans. "You might want to-"

"Introduce our _other_ competitor," Barry cut in.

As soon as the other speedster had spoken, Zoom was shocked when something struck him in the side of his head, followed by a rapid blur of motion. If Zoom hadn't been looking directly at Barry, he would have thought that his adversary had just attacked him, but no matter how fast he thought he was, Barry could _never_ have moved fast enough to make Zoom believe he'd stayed still…

Looking around, Zoom was left completely confused to see someone that he didn't recognise, the stranger standing beside Barry with a nonchalant grin. The figure was a young man, so young that he struck Zoom as being only just out of his teens, and yet he already had white hair apart from some black roots. The new arrival was wearing a tight blue suit that seemed to be made of a similar material to Allen's own, but it lacked a cowl of any sort, exposing the man's youthful exuberance.

"You didn't see that coming?" the young man said, a trace of some kind of Russian accent in his voice as he looked at Zoom.

"Hunter Zolomon, fastest man on Earth Two," Allen said, giving Zoom a self-congratulatory smirk before he smiled at the new arrival in a more friendly manner, "meet Pietro Maximoff, also known as Quicksilver, the fastest man on Earth-A."

"Earth-A?" Zoom repeated, looking at Barry curiously.

"Nobody there was sure of its number in the multiverse and it felt too different from our Earths for me to just call it 'Earth-Three'; I thought 'Earth-A' had a nice ring to it," Barry explained. "Anyway, the situation's simple; Pietro?"

"You want to race Barry and destroy the world?" the new arrival asked with a teasing smile. "Catch me."

With that, the new speedster vanished, Zoom gritting his teeth in frustration even as he hurried after his new opponent. For a moment, the race seemed even as the new arrival weaved around the power plant, clearly having been preparing for this part of the contest when Zoom had been anticipating a more straightforward contest against Barry, but it didn't take long for Zoom to spot Pietro zipping around a corner just in front of his current position. Shifting his direction so quickly that anything else would have been knocked out by the rapid change, Zoom chuckled as he ran around the corner and saw what looked for all the world like a large red-and-white Frisbee hurtling towards him. He could have easily dodged such an attack, of course, but right now it seemed like more fun to let it pass through him to reaffirm how pointless this was-

The impact against his chest was not only so sudden that it threw him off his feet, but he was suddenly keenly aware of a sharp pain that could only indicate at least one cracked rib, if not several. Staring at his chest as he fell to the ground, his eyes widened in incredulous horror as he saw the large Frisbee literally sticking out of his chest, its edge now rimmed with blood from where it had struck him.

"Vibrating through vibranium?" Pietro said, smirking as he suddenly appeared at Zoom's side, arms nonchalantly folded. "I'd ask why you didn't see that coming, but from what Barry tells us, vibranium does not exist here."

"Just be grateful that Stark didn't come along," another voice said, Zoom turning his head to see a man wearing some strange blue suit with a red-and-white waist area that put him in mind of the American flag in this world. "He'd be happy to give you a full list of the reasons why doing that was stupid that only a few of us would even understand; me, I'll just tell you that you apparently can't vibrate through something that absorbs vibrations by its nature."

"You _dare_ -!" Zoom yeled leaping to his feet and hurling a blast of lightning from one arm-

 _Impossible_!

Even Zoom's accelerated mind could only stare incredulously at the lightning-bolt he'd just hurled at the man who'd thrown that Frisbee thing, the bolt being harmlessly redirected upwards and away from its intended target. He quickly redirected his gaze to its new target, but was left even more incredulous when he saw that the lightning was being absorbed into some kind of thick-headed hammer, held by a man in strange silver armour and wearing a ridiculous red cloak as he came towards the ground.

"You would wield the lightning against those who ally with the god of it?" the man said, revealing shoulder-length blond hair and a neatly trimmed beard as he landed beside Pietro and the other man. "Think again."

"Who the _Hell_ are you?" Zoom glared at the intruder.

"Oh, this is Thor," Barry suddenly put in, the Flash appearing nonchalantly beside the other three as he looked at Zoom with a casual smile. "As I said, if you're going to threaten the multiverse, I thought it was only appropriate to bring in some of the mightiest heroes of another Earth I knew to fight for it."

"Really?" Zoom countered, glaring at the three new arrivals, already focusing on the still-unidentified man in blue as the weak link. "Then-"

Even as he spoke, the man who called himself Thor had hurled his hammer towards Zoom, prompting the speedster to shift into superspeed and neatly sidestep the thrown weapon. Smiling at the thought, Zoom reached out and looped his wrist through the strap on the end; once he turned this-

His thoughts were cut short when the hammer, far from responding to his tug on it, instead continued hurtling through the air, yanking him off his feet as it carried him along with it. Even Zoom's accelerated thoughts barely had time to process what had just happened before he was sent crashing to the ground, followed by a sudden kick to the head from what looked like Pietro. Feeling a strange weight on his chest, Zoom stared incredulously as he realised that the hammer that had previously been used against him was now on his chest, exerting such a great weight that he couldn't even focus enough to vibrate through it.

"That hammer may only even be wielded by the worthy, Hunter Zolomon," the man who called himself Thor said, looking mockingly at the speedster. "You may as well abandon your efforts to escape; if Barry Allen could only just move it, you will never be capable of doing anything to it."

 _NO_! Zoom roared mentally, straining against the weight on his chest, his eyes frantically searching his surroundings for something-

His blood ran even colder when he saw someone standing _directly in front_ of the still-inactive Magnetizer, opening a panel and examining it with the cool air of someone who knew about machines. Refusing to concede to this new threat, Zoom vibrated his body downwards so that he phased into the ground beneath him, and then adjusted his position so that he returned to the surface with the hammer now lying a few feet away from him. Now back on his feet, Zoom charged towards the Magnetizer and grabbed the man who dared to tamper with his equipment, slamming the intruder against his device.

 _Pathetic_ , Zoom mused, looking over the man's purple shirt and dark trousers; he was so stereotypically 'geeky' that he actually wore a pair of glasses on top of everything else. _They couldn't even make it Wells or Cisco; they sent some nobody_ geek _to stop me_?

"You dared to try and stop my creation?" Zoom growled at his foe. "Who are you?"

"Someone you made angry," the man said. With those words, he suddenly reached up and grabbed Zoom's arms, pulling them away from his own shoulders with a sudden show of strength that Zoom had never expected from this man, accompanied by the other man's skin turning green and his muscles becoming larger. Zoom tried to vibrate to escape, but the green creature flexed its hands and Zoom was left screaming in agony, his arms broken as he stared at the fractured limbs in front of him. Looking up, Zoom tried to look threatening despite his twisted arms, but the green creature ignored him as it turned around and shattered the Magnetizer with a single punch that packed more power than anything Zoom had ever seen a humanoid display before.

"NO!" Zoom yelled, glaring in outrage at the creature that had just shattered his plans. "You-!"

"That would be the Hulk," Barry Allen's voice cut in, the speedster smiling that same arrogant smirk as he sped up to stand alongside the large green mountain-man. "You remember I mentioned a guy who went through a similar experience to you and ended up a better person? This is him, and I think he's going to deal with your plans right… _now_."

"Right," the Hulk grunted, before turning his attention back to the magnetizer, tearing through the metal plates around the machine's central components before Zoom could get back up. Glaring in rage at the green man, Zoom stood up and prepared to charge, only for Barry to charge in from the side, sending Zoom flying backwards before he could counter the attack. Arms blazing in agony as his accelerated metabolism tried to heal still-shattered arms, Zoom could only watch as the Hulk tore through the Magnetizer as though it was nothing more than paper, the entire device collapsing into itself.

As he watched the fragments of the Magnetizer fly away from its now-shattered frame, Zoom thought for a moment that he would at least have the satisfaction of seeing some of those shattered components injure Barry's allies, but that thought was ended when he glimpsed the other speedster running around, rapidly moving anyone who might be in danger of being hit out of the way before it could strike.

Staring at Barry, Zoom cursed everything, even as he was already making plans for his next move; he could still get back to Earth-Two and create the components for a new Magnetizer once his arms had been re-broken and properly set, and then-

That thought was cut short by the sound of a terrible screech from behind, Zoom turning around to stare in horror as time wraiths emerged from a smoke-like rift in the air above him, all hurtling towards him.

 _Oh no_ … Zoom thought, staring at the approaching Wraiths in horror.

He might have been able to get away with his actions if he'd actually succeeded, as the Wraiths would have been too occupied dealing with the fallout to track the source of it, but actively planning something like that… and the Magnetizer's destruction must have been a beacon to the creatures…

"Barry!" Zoom yelled desperately at the young man in red who was now standing with those four strangers, even the large green thing staring grimly in his direction. "You're the _hero_ ; you won't kill me!"

"I'm not killing you, Hunter," Barry countered, his tone cold. "I'm just not going to bother saving you."

As the time wraiths dived down towards Zoom, the most powerful man on Earth-Two could only scream in agony as he felt the Wraiths take his flesh, twisting his face and form before they hauled him back towards another rift…

**Notes for the Chapter:**

> Hope that worked; I felt 'obligated' to keep Hunter's transformation into the Black Flash intact, considering the role he played in the final battle with the Legion of Doom, but I just didn't see Barry allowing himself to get into a position where he had to create the remnant when he had other allies to call on at this point


	14. Return to Earths

"So… you got your powers in the _Second World War_?" Cisco stared incredulously at Captain America, the various members of Team Flash looking incredulously at the Avengers while Wells examined the mask worn by Hunter's mysterious prisoner. "How… I mean, _wow_ …"

"Didn't we have something like that in this world?" Barry looked at Cisco in surprise.

"Yeah, but from what I've heard our version pretty much drove everyone who used it insane; doesn't really count as a scientific success," Cisco clarified.

"In defence of your world, the only other person who was exposed to the same process as I was _did_ go insane, and he was disfigured by it as well," Steve noted.

"Disfigured?" Jessie asked. "How?"

"His head looked like a skinless red skull."

"…Yeah, that's just gross," Cisco noted, wincing at that image. "I mean, intimidating, but gross."

"Isn't Bruce's transformation based on that process as well?" Barry asked. "I mean, I did a bit research on your histories while I was in your world…"

"I used a variation of it, but… I got a few things wrong," Bruce shrugged, standing awkwardly at the side of the room in a loaned STAR Labs hoodie after the destruction of his own shirt. "Different power source used to kick-start the final process, maybe missed a couple of the details of the serum itself… people have theorised for years that the scientist who created the serum made a few last-minute changes the night before Steve's process and never wrote anything down, so compared to some of the other attempts, I actually got off fairly lucky."

"I… see," Caitlin nodded thoughtfully.

"And what was that thing you used to turn back?" Cisco asked. "I mean, the hammer-guy just showed you that phone, and you-"

"It's private," Bruce and Steve said at the same time, each man looking slightly uncomfortable at the topic.

"Oh… sorry," Caitlin said, nodding in awkward understanding before she looked at Steve with a more curious expression. "Getting back to your abilities, I take it there aren't any samples of your DNA from before this… super soldier process changed you?"

"Not as far as I know," Steve said. "Why do you ask?"

"Just curious," Caitlin clarified. "If your world had prior samples of your blood, they might have been able to properly reverse-engineer it by comparing samples from before and after the change…"

"On the topic of powers," Jessie glanced around the Avengers before her gaze fixed on Pietro, "how exactly did you get here if you're not… well, from what Barry told us earlier, you're not linked to the Speed Force like he is?"

"Correct," Pietro nodded. "Barry and our scientists back home think that, as I do not draw on this 'Speed Force' you talk about, I cannot create rift myself, but can travel through existing one if I move fast enough."

"So you just… ran quickly and followed him through the rift before it closed?" Caitlin mused. "That… makes sense."

"Yeah, I carried Steve and Pietro carried Bruce," Barry put in, indicating the fourth Avenger with a smile. "Thor here has… some experience with crossing dimensions; he said he could follow me on his own steam."

"You travel dimensions?" Cisco looked at Thor with a newly-eager smile. "Does this have something to do with the whole… 'god' thing?"

"It ties in to how the Earth my companions and I come from worshipped my people as gods in the distant past, if that is what you mean," Thor acknowledged. "I have officially abdicated from the throne of Asgard, but I retain sufficient authority to command the attention of Heimdall, he who guards the Bifrost bridge that allows for travel between the realms, and he was able to extend its influence to follow Barry Allen's request for help."

"Huh," Cisco said, looking thoughtfully at Thor for a moment before he smiled. "From what I understood of that, it's pretty neat."

"You know what I _don't_ get?" Wally put in, looking curiously at Pietro. "You said that you and your sister got powers from this thing called the _Mind_ Stone… I can get how that ties in with what you've told us about her powers, but what does being fast have to do with something that should give people mental abilities?"

"The psychological acceleration, for one thing," Caitlin clarified.

"What?" Wally and Pietro said at once.

"Well, a speedster's mind has be accelerated to keep up with the new sensory input they're receiving when they run, or they'd just end up running into a wall or something the first time they moved above human speeds because they'd lose track of what their bodies are doing," Caitlin explained. "In Pietro's case, this 'Mind Stone' much have accelerated his mind to a level where he could safely move at superhuman speeds as well as giving his body the ability to move that fast in the first place."

"That makes sense," Pietro nodded, smiling briefly at Caitlin.

"Ugh!" a new voice suddenly said, the assembled heroes and their allies turning to where the man in the mask walking down from the room where Harrison Wells and Cisco had been getting him out of the mask. "I don't know what's more annoying; being in that thing, or listening to you two arguing about it."

Turning around to look at the now-unmasked man, the Avengers were just casually interested at the chance to see the mysterious prisoner's face, but Barry and his allies were left staring incredulously at the sight of a man they'd seen die just a few days ago standing among them as though nothing had happened, albeit dressed in a manner that they'd never seen before.

"I'm Jay Garrick," the man said, displaying a shabby beard and a dirt-stained face. "The real Jay Garrick."

After a moment, the Avengers realised that all of Barry's allies were currently looking at the traditionally-red-clad speedster in obvious apprehension, as though theyw ere expecting some kind of breakdown.

"What?" Garrick asked.

"I'm sorry," Barry said weakly. "I-I'm sorry…"

As his fellow speedster left the room, Pietro quickly moved after him, barely registering Iris following him as they soon found Barry further down the stone corridor, body shaking with sobs as he crouched on the floor.

"Barry?" Pietro asked.

"He… he looks just like him," Barry said

"'Him'?" Pietro repeated.

"Jay Garrick looks exactly like Barry's dad," Iris explained.

"His dad?" Pietro repeated, suddenly remembering what Barry had told them about Zoom when he came to ask the Avengers for help. "Oh God… I am sorry, Barry."

"It's not your fault-"

"But I can imagine how you would feel," Pietro said.

"You lost your dad?" Iris looked at Pietro curiously.

"My parents were killed when our village was bombed," Pietro replied. "My sister and I only survived by a supposedly impossible chance when one bomb never went off, and we spent the next few days waiting for it to detonate, too scared to even move in case we or shifting rubble brought it down on us, before we managed to escape."

"Oh," Iris said, looking sympathetically at the other speedster before she looked back at Barry. "But Barry… if he doesn't know who he is to you… you want me to tell him that you just had to leave?"

"No," Barry said, standing up even as his posture shook in the process. "No, I can do this."

"OK," Iris smiled at him.

"I'll just be a minute," Barry nodded.

"And we're here for you for that minute," Pietro said, sitting down beside his fellow speedster.

* * *

"There was a dampener in this thing that stopped you accessing your powers?" Bruce said, studying the severed metal mask that had been covering Jay Garrick's head.  
  
"Exactly," Jay said, glaring coldly at the mask that he had just broken in two with one vibrating hand. "He stole my name, my colours… the only thing that _was_ him was that helmet."  
  
"I wondered," Pietro said, studying the silver bowl-like- helmet with small golden wings on a nearby table. "What is this?"  
  
"He said it was his father's from the war," Iris said.  
  
"Ironically," Harry observed, picking up the helmet from the table, "on my- on our Earth, this helmet stood for hope."  
  
"Yeah?" Jay looked curiously at the scientist.  
  
"Yeah," Harry confirmed.  
  
"Well," Jay said, looking thoughtfully at the helmet as he walked up to Harry. "Maybe I can continue that sentiment… take something from him for a change and make it my own."  
  
"That could work," Bruce nodded, as Jay took the helmet from Harry and put it on his head  
  
"It suits you," Caitlin noted.  
  
"Thank you," Jay said, looking around the room. "All of you, for saving me from Zoom… especially you, Flash."  
  
"You're welcome… Flash," Barry replied, smiling awkwardly back at Jay.  
  
"You deserve it, Barry," Steve nodded at the younger man. "Remember; you're an Avenger."  
  
"I just fought with you guys once-" Barry protested automatically.  
  
"Twice," the four Avengers corrected him simultaneously.  
  
"And you joined us the first time to save a world you didn't even know from a threat that you'd had nothing to do with," Steve continued. "You've suffered a great loss, and I'm sorry about that, but if you take anything away from this experience, Barry, remember this; two different Earths consider you one of their mightiest heroes."  
  
"And the residents of two more Earths are proud to know you," Jay added, smiling at Barry in approval, Harry's brief nod somehow the greatest sign of acknowledgement that man would ever give him.  
  
"Th… thanks," Barry said, lost for anything better to say as he looked at this man who was so like his father even as he clearly wasn't. "You know… you helped me even before you got here."  
  
"We did?" Bruce asked. "How?"  
  
"When he… killed my dad," Barry said, swallowing down the pain as he looked at Bruce, "Zoom said that he was doing it to prove his own strength and make me like him… and I used you as an example of how he was wrong."  
  
"Me?"  
  
"Well… you saw your dad kill your mom when you were younger than either me or Zoom, and even as the Hulk, you've never taken that out on _anyone_ who didn't deserve it," Barry explained, grateful that Bruce just gave him a sympathetic smile despite the personal nature of this discussion. "I just… Zoom was ranting about his own strength, and I just told him that all he was doing was lashing out at the world because he couldn't cope with his anger any other way, letting his life be defined by one event when you never let what happened with your parents define your own life."  
  
"I still went into the same field of research as my dad-"  
  
"But you didn't end up… well…" Barry said, trailing off before he could label whatever was wrong with Bruce's father. Bruce might have basically hated his father, but considering that the human Hulk never talked about his parents to anyone as far as Barry could tell, bringing them up in depth would just be awkward at best even if it was to make a positive point. "My point is, you all showed me proof that the strongest decision when wielding power is using it to help others; using it to break stuff like Zoom or Ultron did is just the _easy_ option."  
  
"It's something we all need to remember sometimes," Steve reflected. "We've all endured a great deal to become what we are now, but the important thing is that we work out what we're going to do with ourselves now that we have this responsibility, and keep on being strong enough to use it to defend the powerless."  
  
"And what if you can't?" Barry said, looking at the Avengers' leader with a new sense of uncertainty in his manner. "What if it's just… right now, I just feel…"  
  
"Broken," Bruce finished, shooting a look at Jay that made it clear his own involvement in this conversation wouldn't be welcome no matter how well-intentioned it might be, before he moved over to stand beside Barry and place a reassuring hand on his shoulder. "You showed me that I couldn't just run away from my problems and fears with the other guy; what makes us Avengers isn't that we never fall down, but that we pick ourselves up after we take that kind of beating."  
  
"And if you can't?" Pietro said, smiling at Barry in a half-teasing manner. "It's like the captain said; walk it off."  
  
Looking around the room at the other heroes, Barry finally smiled gratefully at them all.  
  
"Thanks," he said at last. "I… I needed to hear that."  
  
"Do not define yourself by what you have lost, Barry Allen," Thor put in now, Mjolnir hanging by his side as he addressed the young speedster. "Remember the obstacles that you have overcome to reach this point, and be assured that you can overcome the ones you face now and those which are yet to come."  
  
"Exactly," Jay smiled at Barry. "One of the first things you learn as the Flash, Barry; we may still stumble like everyone else, but we get up faster than everyone else when we put our minds to it as well."  
  
"Right," Barry nodded at Jay, his smile becoming slightly broader at that compliment from his father's doppelganger.  
  
"So," Wells cut in, "I get that this has been an important conversation, but maybe we can see about getting everyone home now?"

* * *

"We have to do this all the way out here?" Iris looked around the abandoned development in surprise. "I can get that there are some kind of problem with multiple portals, but this seems…"  
  
"When we're dealing with worlds this far away from our own, it's easier to keep our distance to make sure the portals don't… well, get their wires crossed," Wells explained, as Cisco put on his 'Vibe' goggles and raised his hands.  
  
"So you can open these portals this easily?" Pietro looked at the younger scientist in surprise.  
  
"I'm still learning, but it's getting easier," Cisco said, adjusting his stance before he generated a blue glow from his hands. It only took a few seconds before the glow generated another portal, similar to the one in the basement of STAR Labs.  
  
"Just walk through here and that's it?" Bruce asked. "No speed needed?"  
  
"Not any more than the none-speedsters among you would need to just run anywhere in the first place," Cisco confirmed, even as he gritted his teeth while speaking. "So if you could…?"  
  
"Right," Pietro said, pausing to give Barry a final comradely hug before he ran through the portal.  
  
"It has been an honour to assist you in this battle, Barry Allen," Thor said, before following the other speedster.  
  
"Remember," Steve said as he looked at the forensic scientist, "if you ever need us again, just call."  
  
"Glad I inspired you," Bruce said, his brisker tone belying the gratitude in his eyes before he turned and entered the portal just after Steve. For a moment Cisco suddenly winced and staggered back, the portal turning a brief red as opposed to the usual blue, but the moment passed and it returned to normal.  
  
"What was that?" Jessie asked, looking curiously at Cisco as he closed the portal.  
  
"Just… something at the other end; didn't feel like it was anything important," Cisco said, shaking his head slightly as he removed the goggles. "Probably that Bifrost thing Thor mentioned being triggered once he got back; nothing should have happened to anyone at the other end."  
  
"Right," Wells said, looking around the group. "If that's done, maybe we could see about getting the rest of us back to our Earth?"  
  
"No problem," Barry smiled, walking over to place an arm around Caitlin and Cisco to run them back to STAR Labs; Jay could take the Wells', and then they'd come back for Iris, Joe and Wally.  
  
He'd still need time to grieve once their allies from Earth-2 had gone home, and he wasn't going to kid himself that the next few days, weeks, or even _months_ would be easy… but somehow, knowing that Captain America had faith that he could get past this, and seeing how Bruce had learned to cope with his own pain after suffering greater losses at a younger age, Barry had hope that he'd get past what had happened to him as well.  
  
He had lost his father, but he'd gained new allies and friends, and the respect of the mightiest heroes of a whole new Earth; it wasn't the same, but it was going to help.

**Notes for the Chapter:**

> And there we are; the last chapter of this particular crossover, and I hope it meets with your approval.
> 
> To answer the most obvious questions; yes, the breach reacting that way when Bruce went through it is meant to reference him being transferred to Sakaar to become the Grandmaster's gladiator, although it's up to you whether that was a natural fluke or deliberate action on the part of the Grandmaster.
> 
> On a more immediate note (and one that I'm sure will be more interesting to you all), the approval and support of the Avengers will help inspire Barry to _not_ create 'Flashpoint' in this version of events. Of course, no 'Flashpoint' means no Dominator invasion, which means no initial DC-CW team-up for the Avengers to join, but I won't rule out the possibility of another crossover if I'm so inspired, considering that Barry might still invite the Avengers to his wedding in time to deal with the Earth-X invasion, to say nothing of the possibility of the Avengers asking the Scarlet Speedster for assistance against the Mad Titan…


End file.
